Auto - sticking 3/4 gear on mainshaft

I have noticed that since I have had my 390 Auto, every time I strip the box for inspection (every other ride). The 3rd and 4th gears on the main shaft are tight together. If I prise them apart with the special factory tool (two big screwdrivers ) then it rotates fine. When I come to inspect it again, they would have closed up and both rotate together.

Does anyone know what is worn ?

2nd and 3rd gear are ok, it's just 3rd and 4th. All the gears are a very tight fit on the respective stub shafts, and there is not much wear on the teflon bushes.

I thought the circlips positioned the gears. Do you notice anything when riding the bike?

Yes, the circlips position the gear. But when I rebuild it I make sure the gears are pulled up against the clip. They are nice and free. When I come to disassemble the gear has moved down a few thou and touches 4th gear. The two want to spin as one. But the 3rd gear is really nice and tight on the shaft, the only way it will move is with the special Husqvarna hammer, on e way, and the big screwdrivers the other.

I don't have anything to compare it to as for noticing anything. I can still count the gears. But am I getting the full spread of 3rd and 4th ?
Maybe next time I pull it down I will try a few different parts from my spares chest and see if that is any different.

I have several (ahem!) clutch assemblies in my shed , your welcome to come and have a poke about if you want. I must admit, touch wood, to not having any trouble with these assemblies, none of the spares seem badly worn, unlike the 3 speeds which do seem to have suffered!