Sloppy Denso coupler

[kamocat]

I'm using a denso window motor, direct-drive onto a 2 foot arm. It appears to have enough power (and more than enough speed) for the application. However, the coupler has 7 to 10 degrees of slop in it. (On the two foot arm, that means it wiggles 3-4 inches)

I'd like to drop that down to below 2 degrees of slop, but I want to keep this coupler as a coupler, not a permanent joint. What's a good way to do this?

I tried hot glue. Unfortunately, I wasn't careful enough for it to create a tight fit, and it ended up just sticking it together without decreasing the slop. (I'm sure I can wrench it out, but I haven't bothered yet)

Another idea I had was to use newspaper - this is a cheesy method I use to press bearings into sheet metal when the hole isn't undersized. However, this isn't ideal because it would need to be redone every time the coupler is removed.

Would tape be a good option? Would most tapes squish out of the way too much and develop slop over time?