The 1st 55AX seized on the crank pin and sent debris all over. It was running very rich then as I had just cleaned it.
The 2nd 55 AX i opened and cleaned. Actually, I did the same with the 75AX as well. I didnt open the head, instead opened the backplate and glow and kept immersed in clean methanol for two days. On both I noticed rust on the crank towards the counterweight side. It wasnt much and I cleaned as much as possible with a cotton bud. This same engine seems to have "scratches" in the piston side, but they were not much and will disappear when it gets oiled.
The 75AX may have been lost to incomplete break-in but I have not used it since I cleaned it.

No crashes though

Ameya