I have a very nice MFJ Deluxe Versa Tuner II that I use RV mobile. The turns counter is a O-Ring drive belt which just broke. Current TC is a 3:1 ratio. Reaching out to MFJ they suggested the mechanical TC-11 TC. This counter has a fairly large rectangle zero reset button that required enlarging the pin push hole of the O-Ring TC. After I did this, the gear was still 3/16 too high from the inductor coil shaft gear they provided. One cannot raise the inductor due to the drilled faceplate. There is a possibility to lower the turns counter but that would require enlarging the TC window. Didn't want to compromise the faceplate any further so reached back to MFJ and they said that they will send me another TC. This time, I received a beautiful TC-12 with a 5 digit read out. Talk about fine tuning. Much to my dismay, there is not enough real estate on the Versa Tuner front panel to mount this TC. So back it went with the TC-11. I have asked MFJ to send me replacement O-Ring drive belts and that will have to do. I will take OD and thickness measurements and will post. Everything is possible to mount the TC-11 but it would require more front panel modification than what I wanted to deal with. Hope this lesson learned will help some one else. I would also like to note that it was not difficult to remove the tuner front panel which is needed to replace the O-Ring or gearing. In fact, the roller inductor just has to be loosened and not completely removed as suggested in other threads. Cleaning the roller contacts is highly suggested though. Since the ratio is 3:1 its not hard to get into the ball park on the roller inductor. I just use the old school method of listing for the highest audio signal and fine turn from there. A broken TC drive belt is certainly not a deal breaker.