I have a Craftman Briggs and Stratton lawn mower self propelled (i have only used it for a few seasons) I am having trouble pulling the cord. I never had a problem starting it. I went to start it this year and the cord was extremely hard to pull. I thought it might be the piston that got corroded on the cylinder since it's been a while since I have use the lawn mower( I keep the lawnmower in my garage). I took off the blade, disconnected the self propelled belt and the took off the cylinder head. I turned the engine by hand and the piston looks to be going up and down and valves are opening and closing with out a problem. I did note the piston seems like it was getting caught on something at times when I was turning it by hand (I was thinking a possible bent crank). I changed the oil, flushed the fuel system, change the blade but still having the same problem. I took off the recoil mechanism (pull cord) off the lawn mower and checked it and it is not getting caught on anything. I put everything back together. it is easier to pull the cord then at first but I am still getting a lot of resistance. I then thought it might be the brake for the self propel mechanism. I disconnected the belt for the self propel mechanism to see it the issue was there. that did not make a difference. At this point I am thinking I have a bent crank. I have hit a lot of rocks in the past and the blade was pretty chewed up so maybe the problem is there. When I put the lawn mower on it's side with the propelled belt off and the spark plug off the blade seem to have a lot of resistance when I turn it. I don't know if that is normal. also as I turn the blade it seems that sometimes it frees up for about 1/4 turn and then I get a lot of resistance again. I don't know if that is normal. I don't think it is. Anyways, if anyone has any input on my problem I would appreciated. I was thinking of replacing the crank ( I am pretty good with mechanical stuff) but I just don't think it's worth it. the Crank goes for about $100 w/ shipping. I probably will have to buy a lot of hardware and spent a lot of time doing it when I can just go buy another lawnmower for a little over $200.