This is becoming a common problem. Several members have apparently figured out a bypass to buying a new control module. Basically the problem is an interlock designed to prevent concurrent usage of the external switch and the remote fails to reset. The result is only the remote functions. Replacing the control module is the standard solution as the interlock is built into the control board circuitry (~ $200).
The bypass is to move the ground wire from the switches from the connection on the control module to a chassis ground. This negates the interlock and enable the switches once again. The problem of using the external switch and the remote at the same time is not one I consider an issue.
Here are several threads which supply all the knowledge you need to correct the problem.
Page 4 of the discussion - GTOWag (second post on that page) describes the problem and solution.
http://www.montanaowners.com/forums/...remote,control
Jackel1959 describes the problem and solution with pictures!
http://www.montanaowners.com/forums/...ad.php?t=46515
Even more discussion of the problem.
http://www.montanaowners.com/forums/...ad.php?t=46379