oil in carburetor?

I have a mountfield tuffcut with a Honda gcv135. Had it about ten years and apart from occasional slow start has been very good. however at end of summer engine chugging and clearly sick and took air filter cover off and filter is covered with wet oil. sounds terminal so shut it off. I have it in my mind that it is a head gasket (from my experience with old cars) so started to dismantle but got as far as trying to remove round head before separting crank case but cant get it off and now stuck. |Not even sure i'm barking up right tree as first lawn mover engine I've attacked. seems I might need a puller to continue. any suggestions gratefully received.

duncan
November 2013