Universal M25 Transmision slipping in forward

[sailorjoel96]

I have a universal M25 xp that is a 1988 model. When it is in forward at lower rpm's in goes in and out of gear. Once I increase the rpm's it stays in drive. I have replaced the fluid and it checks OK to the line on the dip stick and is not discolered.
Any help would be greatly appriciated.

 

[dparilla]

How is the tension on the shifter "dog bone" (where the shift cable meets the tranmission and often looks like an dog bone.) It may be vibrating loose. Or the fork inside the transmission may be worn.