Its a bit confusing Mr Luke, but I think both covers have been removed, if he can see the clutch plates AND the chain
TS150 clutch uses 6 coil springs, held in place by tiny easily lost pins and cups ( don't ask!)
The grease will be stuff applied to the chain over the years, as being a pain removing the chain, people just slap a bit more on the front sprocket and let it get carried around. I would clean it out with paraffin. Probably worth removing the chain and washing it too, taking the time to check for cracked rollers although threading the chain back through the gaiters and rear chain case is a pain but if you decide to do it I ( or someone else on here) will talk you through the best way to do it .
What you really needed for the screws was an impact driver and a close fitting bit, takes them out easily and without damage.
Sometimes the end of the clutch pushrod goes soft and bells out slightly and becomes shorter. Worth trying to get it out to check. A quick and dirty way of getting a bit more adjustment is to stick another ball bearing in ( but don't tell anyone I told you
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Come back for advice as often as you need it, there's a lot of experience on these boards and there is usually someone around to answer you reasonably quickly
ES250 Doppelport, ES250, ES250/1, ES250/2,ETS 250, ES150, ETS150, BK350, IWL Pitty, SR56 Wiesel, SR59 Berlin, Troll............ and thats just the German two strokes!
http://thecomeconcollection.blogspot.com/