I have a Stihl KM130 Kombi with the older(good) HT-KM pole saw head. After 5 years of continuous abuse the bearings in the saw head fragged. The shrapnel ate the oil pump too. It looks like I may be able to "save" it by replacing the driven shaft bearings. Stihl PN# {inboard, sprocket end} 9503-003-5190 (6001-2RS) and PN# {outboard} 9503-003-5860 (609-2RS) are about $20 US Dollars each locally, but only about 10 British Pounds ($13 US) each from L&S Engineers. Apparently Stihl platinum plates each US part...
Anyway, I will source aftermarket bearings at about $5 each and reassemble to check the gears for livability. If that works, I'll replace the oil pump and add a couple fill & drain screws so I can run gear oil instead of hoping that the grease happens to find the rubbing surfaces.
The US techs all hate the new saw heads; they said that Stihl is going to revert to the older style this year.
Wish me luck...GM