Here is one I seen again today that some of you'll may see, it's the 4th time I seen it this month , and my part guy told me he has seen a rash of them sold lately , T250 and T300's have a lock solinoid that engages a slot on the spool valves of the tilt and boom at the controll valve to lock the spool in the neutral postion , it is electrically tied into the push to operate button , the hose that comes off the boom by pass valve hits and damages the wire right where it goes into the top of the solinoid and when you shake the machine or hit a bump it makes the machines boom lock up but the tilt still works , so if your machine isn't doing the lock up thing yet I would look for the hose hitting the wire and move the hose by loosing fitting , turning hose away from valve and retightening it , * Don't do this with boom in the air and not supported " as this hose I am telling you about can let the boom fall if it is unscrewed or burst