Motorcycle Repair: 1968 t100c torphy, sprockets, trophy

Question
I have a 1968 T100C trophy 500cc transmission locked up. can not get the side cover off.  Found old manual that said put it in 4th gear and use rear brake to help remove side cover.  Locked in unknown gear and no rear brake.  have tried everthing even a puller and so far cannot remove it.  Any advise will be greatly appreciated. Bike has been setting in barn for over 2o years.

Answer
Bill

Now you know the reason why the thing sat for 20 years. The problem is that there is no way of knowing what happened inside to mess things up.

I'm not so sure about the brake thing. Don't see how that could help, but by putting it in fourth gear (assuming the chain is still intact on the sprockets) you might be able to jerk the rear wheel back and forth and knock something loose.

This is assuming that you have followed correct proceedure so far.

John