ac 200 -- gear 5 6 pop out as well as reverse.

also, under the diesel fuel tank is a 90 degree shut off
brass valve. dirt gets in here and i have to blow it out often. i have cleaned tank and it still happens. put in a gently sloping line with a self
cleaning shut off valve ?

dealer says to put in a fuel pump, but this seems redundant.

any ideas ?

A good friend of mine has a 200 Allis also and it jumped out of 5-6 and also 7-8. We call them 3 and 4 gear. Not reverse. At first it was just going down hill but finally got to where it was in a pull also. Last winter we took it in to get the transmission fixed. They put in several new gears and some new bearings. We didn't know they would also find a bad rear-end gear and some plates broken in the power Director( 2-speed shift) We also put in a new hydraulic pump. It was $8,500 dollars for all of it. I know that was a bit much to spend on the old tractor, but we use it quite a bit and it is a strong old horse. I am just a neighbor who helps him but I drive it quite a bit and we still like it. I am afraid you may have some bad gears and or bearings. Our tank also has some junk in it. I have to take the fuel line off and BLOW into the tank. Put the line back on and off you go. The 200 and the XT190 are known to jump out of gear when the transmission gets worn.