Was working on a friends bike lately. It is a BSA A 10 with swing arm frame. The gearboxes used to be bulletproof, as much as i know them. Must say that the bike must had have a very hard life, because he brought it back home from India. That was years ago and since he spend lots of money and effort to the bike. Had the complete box out and dismantled. Got new bearings, bushes, shafts slipped and all that stuff what was needed. He said that the third gear jumps out then and when, especially when riding with his wife. I did check the gears and changed them to a matching set for the third, because the old ones showed some wear. Also changed the shifter fork and checked the spring tension of the cam plate.The problem now is, that the third gear still jumps out under load. Any suggestions, what i should watch out for ?