Minimum impression maybe too heavy on Sears electric typewriter after replacing belts?

I recently replaced the belts on my Sears Celebrity Power 12 (a Smith Corona rebrand if I understand correctly) that were shedding perished rubber with Gates 3M315 Polyflex V-Belts. The typewriter is much happier now; no more bouncing middle wheel or rattling and the impressions are much clearer. Before the smaller punctuation characters (-\_.,) had about a 75% success rate, now they work great.

The downside is the minimum impression pressure seems to be much higher than it was, leading to the ink bleeding through the paper more than it used to. You can clearly feel the raised text from the opposite side when you run your finger over the paper. I've tried using a few different kinds of backing sheet, but that just seems to allow the characters to cut deeper into the paper and leave a more textured impression without improving the bleed through. The backing sheet has a very clear impression in it as well.

For reference the paper I'm using is Maruman B5 loose leaf binder paper, which is very smooth and 80gsm. I figured it'd work well in a typewriter, but I'm relatively ignorant when it comes to stationary. It seems to fair slightly better than 20lb printer paper, but not by much.

The platen is hard, but not rock hard. I deep cleaned, lightly sanded, and then treated the platen with DIY rubber renew (alcohol & wintergreen oil) which softened it up enough that I can now leave an impression on the platen with my fingernail.

Is this fairly normal performance? Is there any way to "downtune" the impression strength? Should I expect to be able to type on both sides of a sheet of paper at all? I'm guessing that either:

1. This is a byproduct of the new belts (315mm) being slightly different diameter from the originals (310mm & 320mm I think) slightly throwing off the CVT transmission gear ratio that controls the impression pressure. 2. The original belts were a bit stretched out and this is closer to the original performance. 3. Some combination of the two.