Thought I'd start a new thread, but following on from previous.....o
Finally acquired nitrogen bottle this morning (the Boc agent that was saving one for me yesterday gave it to someone else, grrr!)
Here's today's log, so far...

Lower accumulator had about 280psi initially. When I removed dust cap there was sound of air escaping, valve body possibly slight loose so I nipped it up gently. Straight forward up to 550psi.
Upper accumulator surprised me that it had 500psi already, took it up to 550..

Disconnect equipment and put safely away, start engine, step back to marvel at the sight and sound, walk round check (mainly for stray tools and sleeping dogs). Flag up lights out. Apply brake peda straight to floor, 4 Times, flag drops.
Consult literature and search ROOF. Glad I'm not the only one.
Follow procedure for bleeding brakes, I wouldnt say the mucky fluid came out with great force, no bubbles either.
Consult ROOF and compendium of handy hints. Decide pistons in accumulators may be stuck, follow procedure for forcing fluid back to reservoir and venting air.

Repeat charging accumulators with nitrogen. And repeat. Give up have cup of tea and write new post....

My bus number (if any): 1842

So, having had tea and taken daughter to see midwife, who wasn't there and never is on Thursdays, got stuck back in from the beginning.
Did the bouncy handbrake and more for luck, fluid well over full mark. Vented air from accumulators, charged them to 550, bled brakes again.
Turned off engine then ignition back on, flag drop 17mins, read somewhere less than 30 indicates internal leak.
Restart engine flag up light off 20 seconds.
Now for the biggie.... A mere 9 footbrake applications before flag drop. Lot better feel than it was and good enough to drive to workshop to remove hubs for an appointment with Brake house next week.......

My bus number (if any): 1842

9 apps is acceptable, however if the flag drops after 17 mins, it does indicate a leaking accumulator. This is part of the problem of leaving RMs standing around for ages. i have a similar problem with one in Belgium at the mo.

I have overhauled accumulators in stock if you need some on an exchange basis.

Thanks, Roy, so, its accummulator rather than anything else?
Leaking internally or valve? When I vented them there was no sign of oil mist.
If so, how do I determine which needs replacing?
Email me the deal. I'm in London next Wednesday til Friday for collection..

My bus number (if any): 1842

The mystery deepens...
Today, as a matter of interest, I checked pressure in accumulators. Both were reading around 400:'(
So I pumped them up yet again. This time, I remembered to hold valve body steady with one spanner whilst releasing the connector thus preventing any loss at that point.
Flag up and light off 21 seconds
I'm now up to 12 before the flag drops and so far, with engine off ignition on, its 47 minutes and counting with no flag drop.
So, on that performance it would seem there isnt a problem after all...
Self mending, power of prayer, gentle tapping with the universal adjuster.....?

I had self mending reverse gear after a rally, Old Warden I think, at the end of last century so its not that unique an occurrence ;-)

My bus number (if any): 1842

My head is beginning to hurt now...
Set off for test drive, no brakes again, flag up and down like a yoyo...
Fluid level above normal "full" level. Brake pump feels warm, should it be?
Out of interest checked accumulator pressure, now. 650!
Given up on "self mending" theory and going with operator error, but dunno what, followed advice to the letter, thought I had some mechanical aptitude. Maybe a little knowledge is a dangerous thing...
:-(

My bus number (if any): 1842

Yes, a little knowledge can be dangerous. Accumulator pressure will rise when the pump has run as the piston moves along and compresses the air.

when I get that problem I change the accumulators, it's quicker and easier, saves a lot of biggering about, but is a bit more expensive. But it means I don't have to travel considerable distances to fix it again next week!

Hello Ian,

The brake pump should not get hot. A common reason for this is deterioration of the flexible rubber pipes internally creating a restriction.There are other causes, but to start with renew the short pressure hose from the hydraulic pump (the thinner one). You will not be able to see a lot wrong with it until you cut it open. The threaded ends are difficult to obtain.

Hi Ian
I strongly suggest you get someone who knows What they are you doing to look over your brakes.

It's not as simple as just charging the accumulators as there is a set procedures It's important that it's carried out correctly I have posted this information on here in the past.
You can get the accumulators reconditioned even with new cylinders under £200 each if you need to.
If you want some free Advice feel free to give me a call
On 07534 904650
Martin

Either myself or the other roy would be able to sort your brake problems, but I suspect you're not very near Kent.

Thank you, gentlemen for your support and offers of help. It might well be sorted...
My last post has disappeared into the ether. Briefly, I decided that I was happy with the accumulators and that the symptoms indicated fault with the pump.
Changed it, bled brakes and left it overnight for the faeries to check over...
Anyway, this morning I appear to have the best braking I've ever had :-)in terms of flag dropping and feel. Grumpy grandad did go to the kids birthday party after all.
My ex AEC apprentice friend will remove hubs at his workshop so I can take them to Brakehouse on wednesday.

I'd very much like someone experienced in RMs to give it a look over and point out areas for improvement. Mot booked for 6th June, intending to be on tour after that...

My bus number (if any): 1842

Have a trip to Kent, I'm sure we can sort it for you, preferably pre-MoT. What's wrong with your hubs?

Hi Roy....
3 years later and I find your kind offer. Don't want you to think I'm rude not reply earlier, just don't get on the interweb much and then only on a, so called, smart phone. All the brakes have been done over now, new rollers, shoes, no longer oval hubs etc.
Cheers Ian

My bus number (if any): 1842