Starter Recoil Rope Jerks Back (if it pulls out at all)

[Just Jan]

Hello Everyone- I've been using this forum as just a visitor for a few months and have found it to be VERY helpful. Thanks to all of you for that. I've just encountered a problem, though, that I don't see an answer to so far in similar posts:

Lawnboy 10682, Tecumseh engine. I'm attempting to repair for a neighbor. The starter rope is very difficult to pull and jerks back out of my hand in most cases. Neighbor said it's been that way for a while and once in a while she can get it to start, then it runs just fine. I've not gotten it to start at all. Here's what I've done:

removed spark plug - rope pulls easily
emptied the little bit of oil from the cylinder in case it was hydrolocked
checked the flywheel key: removed it, inspected, no problem found
inspected the blade support
replaced the (very worn) previous blade in case it was throwing balance off
inspected crank shaft
ensured blade was not being blocked by debris

Starter rope still jerks and bucks. What else could possibly be causing this? The control cable has a bend in it but still pulls on the flywheel brake ok. I double checked when I had the flywheel off.
Any ideas? Thanks in advance.

 

[Rivets]

Your problem is a partially sheared flywheel key. Replace it and you will solve your problem.

 

[Just Jan]

@ Rivets : the flywheel key is a plain rectangular steel one, rather than the oddly shaped aluminum found in many Tecumsehs. I took it out and neither saw or felt any issue with it. Think I should try it anyway?

 

[Rivets]

Yes, it may not look bad, but could still be causing the problem. Also check to see that the flywheel keyway is not damaged.

 

[chance123]

If changing the key doesn't work, I have found that changing the spk plg gap seems to affect/correct this problem. You can try + or -. Go to the max (while still having spark) to see which way helps or not. Since it is jerking "back", it gives the impression of advanced timing. Perhaps even the coil to FW gap.

 

[Exmark fan]

I would start by adjusting the valves.