just got around to installing the 64a I got at the begining of this year the first time I started it it had a lot of vibration at mid range. I will admit that the first batch of fuel i mixed up I didn' t check my can very good and had some gunk in it that got into the carb before I could shut it down. I had primed the carb and it fired right up and sucked the stuff into the carb. I cleaned out the carb and re worked the fuel system. got the fuel system working right started it agan the vibration at mid range more like it was trying to jump off the table I brought it back to idle I let it run for a few a while because bolts and nuts were coming off the plane. The prop a 20/10 master airscrew clasic was and is balanced I noticed a scuff mark on the magnito put a gage to it on the prop flang 3 onethousand out at the scuff Is the master airscrew to heavy for the engine? the engine starts easy idles low throtle is great but do I need to send it in for a bent crank?