Hi again, Nancy here with an update. I called good old Ray at Seyco and he said he could "not confirm or deny" that the Excalibur blade holders would work on DeWalts. Probably because he is an authorized Excalibur dealer, and not DeWalt. Anyway, I ordered 3 of them, one for each saw, and they work perfectly. Mine are all Type 1 DeWalts, made in Canada, so guess I can't say for sure that they will work on the newer Type 2's, but I'm betting they would.
If I had know years ago about replacing just the set screw and the tiny end of the thumb screw, I wouldn't have tried tightening the blade so much and wouldn't have ruined the blade holder. Those parts are also interchangeable in Excalibur and DeWalt, and available from Seyco. It's called the Quick Clamp Renewal Kit #QCRX and sells for $6.30. There are 2 of each part in the kit.
Sure nice to find this site and be able to interact with so many helpful fellow scrollers!