I thought I'd come back and update on this thread since it was originally posted a year ago!
Well, I had a lot of fun and games. Initially topping up was fine, and then, mysteriously the level would fall again. So I'd top up again - and the frequency at which I had to do this was progressively increasing.
I could never find the source of the leak - nothing was outwardly obvious. So I took the car up to my chums in Eathorpe, near Leamington Spa (Tech-speed Motorsport) and I got Keith to do a complete service. They're not expert on these cars, but they are extremely competent. Thing was, they couldn't find the leak either - and of course, as happens when you visit your doctor - the symptoms miraculously but temporarily disappear. They steam cleaned the engine - everything looked lovely - so on we went. A little nervously I have to say, because you don't loose the best part of a litre of Power steering fluid without there being a problem.
About a month later my wife called me to say that the ZTT had died: no electrical power. Argh. She called the AA, and they jumped the car started and escorted her back home, by which time the battery was completely flat.
Cutting a diagnostic session with a multimeter short, the alternator had died - and, yes, you've guessed it, the Power steering fluid level had dropped again. This time with a tell-tail residue all over the top of the alternator.
Video may have killed the radio star, but power steering fluid definitely killed my alternator!!!
Again, all pipes and unions were dry. There was some dampness associated with the PAS pump pulley. Only one thing for it: replacement!
I was going to do this myself, but this was now Feb/March, the weather was cold, I had no time and frankly no patience. So I ordered some bits from fleabay... new accessory belt (old and fluid contaminated), new alternator belt (fluid contaminated), new second-hand alternator (fluid contaminated) and new second-hand PAS pump.
Several thousand miles later and all is well again. The "new" PAS pump is noiser than the one it replaced - but at least it doesn't leak and it does provide power assistance! It coped admirably with Alpine switch-back hairpins too - repeated going from lock to lock with each flowing corner - absolutely brilliant
So, in this case, the problem was indeed the PAS pump. Unfortunately I didn't get the old failed one to do an autopsy on, but there must have been a seal failure.
Interestingly, I now have a new steering issue. There is a wheel wobble at around 70 mph (you can drive through it, and only effects a narrow speed range: I suspect a wheel balance problem - probably lost a weight at some point). The second is a soft "clunk" which is both faintly audible inside the car and palpable through the steering wheel as you steer from side to side from the straight-ahead position.
There is no palpable wear in the bearing, nor in the TREs/ball joints that I can feel. Upper strut bearing? I am not sure - but the problem I have doesn't seem to be quite the same as described elsewhere on the forums. Steering rack?
All I can say is, I really must love this car!!! LOL
