Ok, I might know the answer to this question... I recently took mine apart due to thinking one of the gears were stripped. But I found that the last gear on the trans. (the one that hooks up to the drive wheel) was merley pressed-fit on.... There are no securing fastenres what-so-ever. So the gear was slipping on the shaft....and not allowing movement....Im guessing this is the problem with the HL's pullling to the left or right....the gear on either gearbox is slipping...