Still had the problem of the tuning.
With the PST you turn a collar on the barrel to bring the proms and surface details into view, you then use the focuser on the back to make them sharp.
On my PST the proms only come into view when the collar is turned all the way clockwise (when standing at the eyepiece end), there just isn't quite enough travel in the collar.
Feeling brave after my previous adventure, I followed this guide:
http://home.freeuk.com/m.gavin/pstfixx.htm
It was pretty easy. I used the Boa Constrictor to remove the gold tube - (much easier to remove than the eyepiece holder!).
Then being careful not to touch the etalon thing, I rolled back the rubber grip, and screwed the whole assembly back together.
I undid the screw under the tamper seal, and removed it completely and slid the collar off.
Underneath are adjustment holes. I rotated the adjustment ring 5 holes clockwise (looking from eyepiece end) and put the collar back on, screwing it into the new hole.
Oh my God what a difference!
The proms come into view now at about the midpoint of adjustment rather than at the end. I can adjust them to be so much more visible, it is like a new, better telescope. I can't believe how much better it is.
I'll probably be spending the rest of the day observing!
Thanks to all the PST hackers out there, without your guides I would have been happy with quite a sub-par experience as I wouldn't have known any better. Now this thing really rocks!