Here’s how I got mine working better. This may void your warranty, and only undertake this if you’re comfortable with electronics.
So I recently bought a used Rytm. I already have a Tempest, which has some of the best pad action, so I had a good baseline to compare to. Unfortunately the Rytm definitely had some issues with the pads. In my case, some were triggering better than others, and different velocities.
I decided to do some investigating. First, I removed the top panel, by removing the hex screws from the front plate. Next, I carefully swung up the panel, and disconnected the two ribbon cables to free the front panel (noting the correct position of the “red stripe” on the cable. Next, I removed the silver screws from the circuitboard on the top panel that I had removed. All of the screws have to be removed and there are literally dozens of them - the majority in an area that is obviously the triggerpad area. In my case, this is where I noticed the first problem: some of the screws has gone loose, and were far too easy to unscrew. Others were clearly seated properly and gave good resistance as I removed them. I could tell that some of the pads weren’t making good connection at these loose areas. After removing all of the screws, you can now remove the circuitboard and note the pad assembly: a block of elasomeric rubber (the pad surface) that makes contact with a a carbon-impregnated sheet. This sheet is what makes contact with the sensors on the circuitboard and triggers the sounds. Carefully note the orientation (dull side up) of the carbon sheet.
Gently remove it and clean any debris with a soft microfibre cloth from the sheet. Next turn your attention to the circuit board. In my case there was years of dust and crud there - small, but enough to inhibit the contact with the carbon sheet. Using Isopropyl alcohol, and lint-free cloth, I gently polished the contacts on the circuit board to ensure they were clean and clear. Finally I gave it all a blast with canned air, for good measure. Next, reassemble in reverse order. Be sure align the carbon contact sheet in the correct manner. Be sure to tighten but not over-tighten the screws that surround the pad areas, working from the center parts of the pads to the outer, to ensure the circuit board bolts back on perfectly aligned.
In my case, it made a substantial difference in the way the pads played.
That said, it is clear there is still some software cross-talk filtering that still makes the pads less sensitive than they should be. Even after fully cleaned and working perfectly, the pads are not as accurate as the Tempest.
Hope my experiments are useful to someone else. I’d rate the complexity of this fix/cleaning about a 3 out of 10.
Cheers!