I had that issue.
Change the mounting bolts to socket head.
As far as bearings, no need to buy expensive bearings.
The solution is to convert the PRESS-FIT bearing fit to SLIP-FIT.
Before installing bearings, ream the bearings' mounting holes slowly with sandpaper, until the new bearings slip in with a little resistance.
Also, lightly sand the shaft on the friction rollers, until they slip into the bearings.
If you don't sand the 1.5" rollers, you'll never be able to remove the roller from the drive housing without a press.
Then you can buy cheap bearings and replace them every few hundred miles.
ANNND, you can change the outer bearing without removing the engine or the friction drive housing from the bike!
Do this, and you'll sleep well.