Hi - I had the same problem. you have to dismantle the unit untill you get the black plastic mount with the clutch drum on one side and the drive gear on the other. then you have to lock the drum by putting a small screwdriver or somthing similar through the hole and locating it in the locking hole. Afer that you have to use a small adjustable or spanner to unthread the gear from the drum. (this is hard work because they locktite it in the factory but it will go eventually). if the gear is old and britle the head may sheer off so then just use grips to turn it off. once you have that unscrewed the bearings and gear should push out of the plastic then you need a press to push the gear out of the bearing. you can get the correct gear from - http://www.mowermagic.co.uk/acatalog/McCULLOCH_Virginia_Spare_Parts.html. once you have done that nand have the new gear just reverse the process to put it back in.
It is harder to get back in than it is to get out so BEWARE! Your local Husqvarna dealer will do this for you but it will cost! Hope this helps.
Matt
May 2009
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