Got my Massimo T-Boss 550 back. It took a while, almost 2 1/2 months. The problem causing it to be locked in 4 wheel drive was the front Wheel drive Servo. The shop I took it to is the only shop in my area that works on them. The shop seemed to be really busy, as every time I called to check in I had to leave a message. Only answer I got was "waiting on parts" I finally drove to check up thinking it may have disappeared. When I got there It was sitting outside, but the shop was full with all brands, plus three Massimo's . The owner was loading up a trailer to deliver to their owners. Yes, he does pickup and deliver. His employee told me they had tried to unlock the front end with no luck. The new part was in, but they thought they would have to return it since they said they checked the old Servo and it did actually work when tested not installed. They wanted to show me. Well when they tried to show me the old unit, which only had 27 hours on it, did try to work. Well it didn't . They put on the new one and low and behold it worked. I test drove it, worked. I am hesitant to use the wheel drive completely locked up, but the few times I have tested it, It works. Glad to have it back and I am back to spraying my fence lines. The weeds had gotten out of hand. To many miles of fence line to spray with a hand held pump. All caught up now. Fingers crossed that this was a fluck !!! The shop owner said he will be becoming a Massimo dealer in the near future. They are good units if gone through and serviced before the sale. The ones sold strictly through a certified dealer should have all the minor adjustments done with all oils checked and everything lubed before sold. Cost from an ATV./UtV dealer may cost a couple hundred more, but worth eliminating the issues.