Frank , it sounds to me like that you might have 2 electrical issues . Check the 3 pin voltage regulators plug connection , they sometimes get corroded . With the engine running 1/2 throttle or above the two outside pins should read around 24 to 28 volts A/C . The center pin should read 12 to 14 volts DC .
I'm going from memory but those voltages should be close and vary depending on engine RPM's .
When checking the center pin make sure you find a good clean area for the ground ( black ) probe on your voltmeter. If you have the AC voltage but nothing on the DC side (center pin) then your regulators bad .
As for your cranking issues , sometimes the PTO switch gets corroded and gives the appearance that the neutral safety switch or key switch is going bad . The PTO switch has contacts in it that close in the off position , and if the PTO switch plug has corrosion it won't crank .
I have a cub 1450 which uses the same wiring as your 1250 and I have to sometime wiggle the PTO switch while its in the off position to get it to crank. Especially if its sat for a while as it appears the contact inside my switch oxidize after damp weather .
It appears to clean the contacts after I turn the PTO on and off a few times , and I've learned to live with it .
Good luck , Jess
Edited by Jlaws, November 24, 2013 - 10:48 AM.