Why won't my machine stay in 3rd or 4th gear?

[Devlh Laveighn]

My machine won't shift into 3rd or 4th gear. Sometimes I can get it into 3rd by shifting through neutral, but it only stays there for a few seconds before downshifting. The brake pressure switch also started blinking today. I just bought the machine & it has 5,051 hours on it. I've already ordered filters for a full service, but I'm wondering what could be causing this issue.

 

[Jayne_Monie]

I'd start with the basics-change the transmission filters and check oil condition and pressures. The blinking brake pressure light could be putting the transmission into a protective mode and preventing 3rd and 4th gear engagement. Also inspect the brake pressure switch and wiring before assuming it's an internal transmission problem.