I know my transmission in the 330 has a fail safe, and when somethigns wrong it wont shift above 3rd gear.
Maybe its the same in the 735, maybe the switch in the transmission went out somehow?
try to disconnect and reconnect the battery?
We all get the urge...Saturday early morning...nothing to do till noon...
The aural sensations of 1st gear WOT
**CGM **(Certified Garage Mechanic)