Item 15 bolt may be self tapping into item 65. Items 13,44, and 56 assemble into a belt guide for one of the idler pulleys which self taps into item 65.. And the entire sandwich connects to the frame using item 11 bolt and up through the frame with items 43 and 21.
Dave just for a heads up. The valves are suppose to overlap close to TDC. It has to do with making the engine more efficient. But the sheared flywheel key would cause the plug to spark at the wrong time, which could cause popping through the carb.
Lets back up and start with making sure the battery is actually good. Need to have it load tested to check output. And that doesn't mean with a volt meter because you can have 12.7 volts with a meter and drop to 0 under load. A clicking sound could also be a safety switch or even the fuel...
The 2nd picture is item 64 in this diagram And the 1st picture is part of item 67 https://www.partstree.com/models/247-273270-131278xs099-craftsman-t1100-lawn-tractor-2018/drive-7/
If the valve clearances are set correctly, and I would double check. And still no decompression bump on the intake valve which in this engine is the bottom valve I would highly suspect broken ACR.
When you first posted I was assuming Alternator which would be more stable voltage/current. But if you are running an actual generator, those voltages are very typical output.