The engineers who rebuilt the blower removed it sealed the sides in a press and applied 9lb pressure into the blower there was no air leeks.
Many of them out there still running just fine. They were marketed as a disposable and many parts are hard to find but with proper maintenance most any
Most any 2 cycle motor will run backwards. Are you torquing the flywheel nut to spec? All it takes is a little crease in the flywheel key to throw it
Put the engine at top dead center #1 piston,
take loose part and dist to friendly neighborhood welder.
I have a 90 horse Mercury that fires on the top cylinder whenever it wants. Checked coil packs and they are good. Any help would be greatly appreciated.