Lever is pretty flimsy. You can order a whole new belt tensioner assembly from Ryobi for $15 plus shipping (as of this writing).
https://ryobipower.ordertree.com/model?modelId=59621&brandCode=RPT
^Click “General Assembly” in the dropdown.
However, I decided to print just the lever because I figured the plastic on the OEM part would just break again. I had to use a hacksaw and come up with some pretty janky solution to reuse the hinge-rivet thingy from the original part. If you figure out a better solution and want to modify the CAD, go right ahead and edit the part in OnShape:
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Props to Ryobi for having replacement parts available and well documented. Too bad they didn't design it right in the first place 😂
The author marked this model as their own original creation.