The issue may be up to URC to correct. Logitech chose a very rare protocol, and it seems that the "consistency" that remotes reproduce its timing varies.

The original codes I captured work find on classic Prontos, but were erratic on the Pronto NG and MX-700/800/850. Re-learning the codes on a Pronto NG corrected the issue, but then the codes were too "twitchy" on Pronto classics.

My guess is that the Pronto classic learned the codes at (for illustrative purposes) a speed of "10" and then the Pronto NG played them back at a speed of "8" which was too slow for the adapter to understand. Then I learned new codes which worked on that model at "10", but if I transported them to the original Pronto they played back at "11".

I'm guessing that the MX-6000 is playing them back even slower... maybe a "6" on the Pronto Classic codes and a "8" on my new Pronto codes.

URC may have to create a new database code for this that is reproduced at a consistant speed on their remotes.

I'd like to get John Fine involved, he may be able to figure out new codes that might work.