Because TRX's use such large tires/wheels, wheel bearings would be the first thing a guy ought to check out. A guy could jack that wheel up off the ground. Put his hands at the 12:00 and 6:00 positions, and push/pull in/out at the top/bottom vigorously...with force. If it moves at all... it's the wheel bearing. Then it's a matter of replacing.
Even then, however, a wheel bearing can fail over time ...can be as long as months...or minutes. Usually not minutes. I drove back from Denver to WI on a wheel bearing that was failing. When I got back the tire wobbled in/out a LOT raised in the air! LOL.
Having said that, if there's the possibility of putting all 4 wheels up on jackstands, a guy could take a long wooden stick, say, a broom handle, and place it on the hub on the inside of the wheel (as the wheel is turning) and the other end to his ear. If the bearing is failing a guy will generally hear (transmitted through the stick) loud whirring sounds...if not outright grinding noises. That's an old-timer's way to hear inside the bearing. It works. Obviously yer mechanic or whoever should observe all safety precautions.
Check both sides. Also look for any oil leaks or 'wetness' on the F. Pass side front axle.
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