Yamaha DTXpress/DTXplorer/DTXtreme

Since the "older-original" DTX group has gone away, I thought I'd post this here.  I have a DTX 2.0 set (original owner for many years), but just recently tried using the MIDI sounds, the ones you can actually tune to A, B C#, etc.  Once I set up a kit to do Glockenspiel, or Timpani, etc., and then go to some (not all) of the other kits, and then go back to the Glock kit, the Glock sound gets replaced by the default GrandPiano.  Sometimes it just gets changed to another sound, but mostly it resets to the default. Has anyone had this problem ?  I have two drum modules, the original and an e-bay-purchased one, and they both act this way, but only with some of the 16 MIDI channels, apparently from 11 and higher. 

The details are:

1) Go to UTILITY Page, MULTI, go to one of 1-16, e.g., 14, select Glocken.  No "saving" is required on this page - it's automatic.

2) Go to a drum kit, e.g., 5. Go to the page (I'm not at home w/manual) where you select the MIDI channel, which is 10 for most kits, the "Drum Kit" channel.  There is a kit that is preset for Vibes. It always stays Vibes, so I'll have to see why.  Select the same channel as in step 1) (14). Do the 3-button-save (STORE-PLAY-YES).

3) Go to another drum kit that has a MIDI channel other than 10 already set to it, like Vibes.  Go back to kit 5, and the Glocken sounds revert to GrandPiano, or rarely, another sound, like FingerBass.  That I can tell, when only going to MIDI-Channel-10 kits, and then back to the Glocken kit 5, the Glocken sound remains.
When choosing a lower MIDI channel, e.g., 4-5-6-7, there seems to be no problem.

4) Return to UTILITY page, and see that channel 14 has in fact reverted to GrandPiano. WHY????????????

Here's a possible parallel.
There are 64 drum kits.  The first 32 you can change/save.  With 33-64, you "can" change them, but they're not permanent, i.e., you cannot "save" them. When you go to another kit, and return to the one you "changed," the changes go away.  The MIDI channels appear to be behaving that same way.  Channels 1-9 you can permanently change (that I can tell so far), but 11-16 you cannot -- doesn't make sense that there would be a limit, especially an "unadvertized" one.

I'm in a musical this week and next, and this is the first time I've needed Vibes/Bells. At first this problem meant I couldn't give the folks the sounds I told them I could, in addition to the regular drum kit sounds.  Hopefully the work-around I discovered will continue to work.

I noticed this behavior a several years ago, but thought I was doing something wrong, and really didn't need the MIDI sounds at that time.

Dave H.