Deutz 6207 - stuck gearbox

[exyfeplin]

I need some help with a gearbox problem in my Deutz 6207. The gearbox is stuck in Low range and it seems impossible to shift it, even with the top and bottom gearbox covers removed (and using various levers to try to shift the gear clusters from the top or bottom).

I obviously want to avoid splitting the tractor if possible!

Does anyone have any advice about this?

Many thanks.

Paul
Australia.