904 trans problems

Not just the governor ( but could be that also)
Dirty and sticking shift valves can cause this on both of your transmissions.
You both need to pull the valve bodies and rinse them while manually moving the valves against their springs.
A pocket screwdriver or metal pick works well for this.

If a trans blows up it should also get a new converter (or flushed with a machine) and the cooler lines rinsed and blown out.