NT,I got a nt 254 too,with about 570 hours,we got something in comman than don't we,,,,you talking about the leak is around the arm joint it self,,wonder why tightening the set screw would stop a leak someplace else? Probably a seal of some kind there,shouldn't be a hard fix.Maybe it just pushed it over a little? Hows your tractor running,,you did know we got more hours on ours than 90 percent of the chinese tractor owners on these boards?,,Mine has never failed to start and never broke down,I have never adjusted clutch,,,did the valve/head bolt thing about 3 years ago or so,,really for no reason also,,,,never had a leak in a tire even,,,still got original raditiator hoses,,have put new battery,new alternator belt,new little rad. bypass hose,,never blown a fuse either,,it does have a mystery oil leak out of bell housing weep hole,been dripping at various degrees for about 4 years now,,never have to add any,it is not getting on clutch,pretty sure its trans oil,,,,,how old is yours,got mine about 4 1/2 years ago,,,,thingy