Hello, I recently bought a used Gamefisher 7.5 (217-586612, cover says 5hp but factory tag inside says 7.5, believe it's a Tecumseh). The guy I got it from had a recent video of the motor starting and running on the third pull, and told me the compression was at 120psi. Took it home, got it to rumble a couple of times but never for more than 2 or 3 seconds or so. Heard a couple of backfire sounds once or twice, which I assumed was from lack of fuel. Discovered there was a problem with the fuel line (he had swapped out the line from the external tank and the new line had the fuel bulb pointing the wrong way, plus the adapters were cracked) and replaced with a new bulb.Thought I'd be good to go after that, but when I pull to start, the cord pulls pretty nice the first time, but then hitches and catches on subsequent pulls and is very slow to retract. I pulled the spark plug, saw what appeared to be some fuel or oil on there, then went to pulling the cord with the plug out. When the plug is out, the cord pulls nice and smooth everytime and retracts as it should. Then once the plug goes back in, I get the same hard pull and slow retract issue. Needless to say I can't get the thing started either. Any ideas?