I would assume you will have to open up the trans for that, when you say other gears you are meaning 3 and4 not forward and reverse thru a shuttle shift.
no shuttle shift option , but the forward reverse hi low shifter works good , transmission works on third gear ( too fast for snowblowing )
, when I try to get firs and second gear tractor stops after clutch released , I will remove the top of transmission this week end to see what is wrong with it