Tractor Repair: transmission stuck, massey ferguson 65, hidden surprises

Question
My older model Massey Ferguson 65 has stuck in 1st gear The hi/low shifter is fine  I have taken the filler cap off and tried to pry around but not sure what I'm doing.  any advice

Answer
You may have to take the entire shifter cover to be able to see what might be causing the problem.
There is nothing to worry about when you take the cover off, no hidden surprises.
A lot of the time the gears get worn and are slipping past each other when you shift.
Let me know what you find out
Sorry it took so long to answer your question