You should have started a new post rather then tag on to this old one. You may be correct that it is hitting the seal. It should be recessed slightly below the case opening. Also the flat side of the sprocket goes to the outside.

 

The Good thing is parts & Manuals are around for the shovels,so as long as you get a factory manual which is much better than the others you should have no problems!

 

tks partners..but I had done everithing (Clymer and Hannes manual) the only different that I had done is to change the main drive bearings (not pins)..the sleeves has a "key" I have to install or not?

 

As for the frame, If memory serves me (which at my age it sometines doesn't) pre 1970 didn't have a number. the vin on the engine will tell you everything about it. If you need to know anything about your bike they will steer you in the right direction there.