I just discovered this thread. I had the same thing happen on my mower. Broke two adapter bushings. Everyone told me that I was crazy, couldn't possibly be seeing what I was seeing. Each time it happened the flywheel shear pin was broken as well. The blade did NOT hit anything, whatever was happening was internal to the engine. I also couldn't find anything obviously wrong with the engine. What I ended up doing was polishing the end of the crankshaft and the internal part of the flywheel, then torquing the heck out of the nut on the flywheel when I reinstalled it. That was two years ago, and it's been running ever since. I don't know if it's the same issue, but it feels better to know that I'm not alone!
Interesting, the blade adapters are fragile !
In my case I was the cause of my misfortunes, 1st I put the blade on with an impact gun set on the highest torque setting, I should never had used the beast of tool. I broke two adapter on the same day. ( other mower) Yes is used a proper torque wrench after.
I 1st bald adapter I got was a part purchase on Amazon that come in a MDT packaging. I found a local store which sold me a similar part, new part on the bottom , it does not have the PS mark on the "powder pressings".
top view of the new part :, it's got rust but looks like the same "powder pressing". ( I now realize this new parts of made to break on stress so the crank is saved. )
I re-installed the blade on the original body this Yardworks mower came with. This was the 1st time in over 1 year I had the all the original parts together.
I was able to cut some grass. I have lifted the curse on this mower. Its going back to my brother.
Fascinating how it took me over 1 year to get fix this, in retrospect it should not have taken more than 30 minutes !
I have learned a few important things : always a good idea to test a mower with the original parts, motor body combo and use a torque wrench not an impact gun.
