P38 brake problem

Hi, new to the forum and had a good look around for previous posting regarding my brake problem. I have a 2001 P38 which recently started having a spongy brake on applying slow pedal pressure. Occasionally it will not be spongy but a hard push with a small "kickback". A pump runs every second press of the brake pedal, is this a big clue to a failed Accumulator? I have changed the Accumulator, but it is not guaranteed as it came from another P38. The owner did say it was new, but I'm not so sure.
There are no ABS fault lights showing, just the normal startup lights which switch off at 7ish MPH.
It appears, by checking this and other forums, that the Accumulator is usually at fault.
Any suggestions please?

Cheers

Kenny

Hi and :welcome2:

Brake pump WILL run on 2nd press- it is a compressor, not servo as on "other" cars. Have you tried bleeding the brakes - if not, good start point, but take care.......not like others, see RAVE for correct method.

Thanks Ridesafe, not sure if the mechanic did bleed the brakes properly. I gave him a printout from the RAVE CD to follow. He hadnt done one like this before so maybe a second try would sort it. I'd try myself but the last brakes I bled were in the mid 80's on a Vauxhall Chevette!
I thought the accumulator would hold more "charge" than every second brake press causing the pump to run. My understanding of the circuit must be wrong.

Cheers

Kenny