Similar to some of the others, on an Aqualisa product?

It's certainly interesting to see all the other questions on the Aqualisa products, as some of the problems are the same as mine. We have a shower with the grey box digital processor. It has just passed its 5-year guarantee, and during that time we've had to call out an engineer 3 or 4 times. Our problems in the main were the 'going hot and cold' syndrome. In my naivity I only asked the engineer the last time what the problem was. He said it was the filters in the hot and cold flow pipes into the processor box. He also said that "if it happens again, you can just take the filters out and give them a wash", which he probably shouldn't have said, as it stops us asking for an engineer next time, at £100-£200ish. The hot and cold syndrome might have started again, so I decided to try what he said (I still have the original paperwork on which is shown an exploded picture of where the filter and valve are). I turned the small screws on top of the black plastic valves, to turn the water off, and then undid the "hand tight only" big black plastic washers that are flush with the box. This then shows more of the copper pipping. Unfortunately that's where I got stuck. I couldn't then get the piping to come out of the box. I'm sure there's no other washers, so I imagined one just pulled them out, but they wouldn't. Fearing I would damage something else I left it at that point. Does anyone please know the secret of exposing the small washer, filter, and valve? I was also interested to read about the "iron ball bearings" (in-built obsolescence) in the valve. Has an answer been given (by Mick?) as to the size of the ball-bearings, where to get them, and how they go in the valve? Thanks