The engine alignment done by eyeball back in 2006 for the Honda repowering held out until 2013. During the summer, I noticed that the driveshaft's front rag joint was starting to disintegrate.
I bought replacement rag joint set (PN 922-3000) and the old and new parts compare like this:
The driveshaft fits inside of the repowering kit's adapter so I had to remove the engine to be able to change the rag joint.
Besides destroying the rag joint, the misalignment also wore out the front universal joint (flange assembly, PN 903-0204).
My neighbour is a millwright and I asked him to help me align the engine properly. He set up his dial gauges on the driveshaft and the engine adapter and found that the front of the engine needed to be raised slightly. Adding a washer under each of the front bolt holes brought the engine into alignment.
While the engine was out, I took the opportunity to install a sensor for a future oil temperature gauge.
If you're repowering your tractor, have someone who knows what he's doing help you with aligning the driveshaft.