Gary--
I hate to hear that you're having issues with your TST system. I've had the TST 507 for several years with no real problems, and I've recommended it to others. I get the occasional false audible alarm, but they're rare and will cancel instantly with a button push--when I look at the display, it's reading correctly, so I think the alarm is triggered by a momentary glitch in transmission of the signal. I definitely don't use the anti-theft caps because of the extra hassle to remove them--and without them it's simple to pull the caps to add air. Never had a problem with losing a sensor.
Regarding an internal system--no doubt that a good internal should be more trouble-free than the external units. In addition to the TST internal that you mentioned, I see that the eTrailer site lists a complete internal system from Tuson. Also, I see that Tireminder has just released an internal sensor (Part # TM36FR) that is supposed to work with all of the Tireminder systems (that previously had only external sensors). That unit is also listed on the eTrailer site. I assume that one can buy any current Tireminder system and then use the internal sensors.
Mike
