But it wasn't a major problem.
I'm a fan of the fun Projects pinion bearing, but it does sometimes include this little complication. Some drive shaft housings have protruding welds inside that interfere with this set screw when the shaft turns the collar.
John covers this in the instructions. A little but of filing down the protrusion soon has everything turning smoothly.
Glad to see you back working on the runabout, hopefully the rest of the job will go smoothly.
Steve there was a thread about this same issue about a year or two ago. I did the same with mine with a small rotary grinder.
Everyone of those FunProjects bearings needs that rasping or grinding done to get it to revolve silently
Some of the tubes are full of weld spatter right in the wrong place!