Fine valve grinding compound will do it in minutes.----Remember , the key locates the flywheel for proper timing.----The flywheel is driven by the matched locking tapers.
How long have you owned this machine?---Tested VRO in service ?------Mixing at 50:1 in the tank?----You need to post exact information.----What are the compression values today ?----Does spark jump a gap of at least 3/8" on all leads ?-----Checked the flywheel key?----Was this machine always...
???----Not sure how you determined that a 9.9 HP will fit on the 7.5 HP midsection ----Because it will not fit !!-----And the " super 10 " was not a 9.9 on a 7.5 midsection.-----Sorry --you are sadly mistaken on these 2 topics.
This process starts with a compression test.----Post your actual values.----There have been issues with # 2 cylinder.-----And does the telltale hose come off the exhaust manifold ( side off the block ) , or moved to the top of the block?
I can not see or touch your motor.-----I believe the clutch dog is rubbing on either reverse or forward gear.-----Easy to adjust.----If that is not the issue then you need to investigate.