Hellfire and Trondster, thanks very much for all the detail on your experiments and sharing it with the rest of us.
Tonight, I finally tackled converting my bass drum. I'm guessing Alesis has been paying attention to this forum! There is a groove now cut into the 8" pad base for the wires. I didn't have any resistors, but there was a heap of glue covering the circuits the wires were soldered to. You are right, the de-soldering isn't even an issue.
When I reassembled everything and tested it out through the module, I wasn't getting the impact I was hoping for. Unless striking in the dead center of the pad, I wasn't getting anything. As this is the bass, I wasn't concerned with it, but would be for the two 10" pads.
I did follow your example settings, Trondster, and that helped as far as picking up more of the beater, as did tightening the mesh head more. One thing I noticed was missing was the "slap" sound, but then realized it's because there is no longer a mylar head with metal plate close behind it! I needed to undestand I wouldn't have heard that sound on a recording or through my PA anyhow.
A couple questions:
1) Should I be filling in the hole in the grey foam with some of the leftover white foam or leave the hole there? It appears you have the hole in your photos. For some reason, I thought I had read to fill it elsewhere.
2) I cut the hole in the white foam a bit wider than a CD (about 1" in from the outside). I'm wondering if I cut too much out? The metal plate is still touching some of the foam, but not as much as in your photos. Does that affect the sensitivity, or only if I added a piece of the thin foam like you outlined in your experiment that didn't work?
Thank you both again for your help!