2510 and 3010 no 3rd gear

[hunter1464]

I have a 2510 and a 3010 with the same problem. Neither will move in 3rd gear. It seems they try to engage but then nothing. All other gears on both tractors work fine both forward and reverse. No issues. 3rd gear has probably had the most use of all gears on both tractors if that helps.
Thank you

[Tx Jim]

First thing to do is check for looseness & adjustment in shift rods and shift quadrant.