Can anyone tell me the correct air pressure for front forks? Have 1988 nc24 only 20K on clock. Just had new head bearings and seals fitted but forks seem tired and soft with not much rebound control. Tookit back to my service guy who has just put some shims at top of springs (11.5mm) and current air pressure 6lb which has made things a little better but I'm sure they could be better.Would new springs help? Are they available. What grade oil should they be running? Not sure what he's put in but would have thought he used the book for reference. Would a heavier grade make much difference? Any thoughts??