Governor on a '41 B

My problem is this, when mowing or even going up a hill in 2nd or 3rd, the governor doesn't advance the throttle. It just idles down and eventually dies. Any ideas?

Perhaps related, but I can barely pull my 5' BMB rotary through mild fescue/prairie/assorted small weeds, etc. (To put it in perspective, I had been able to mow it with my old 12hp Massey lawn mower.) Should an old B be able to handle a 5' brush hog or is this too much mower for the tractor?

A govenor does not advance the throttle, it restricts the throttle. The rpm's forces the weights out which pushes the thrust bearing against the fork which in turn closes the butterfly inside the carb. The external spring tension applied by pushing the gas lever forward will increase the rpm's. As the engine rpm's slow down from load the force is reduced on the govener weights and allows the carb. butterfly to open, but only to what the tension is on the external spring.

It seems that all the increase in RPM is from notch 2 to about notch 5 or so. After a point, I get no more increase in RPM. BTW, The gov. is...uhhh... disabled at this point and I'm mowing at full throttle.

How long should that external spring be at rest? Any idea of the poundage?

As for a spring test for tension, I know of none. The setting is made by bending the cross arm to get the correct RPM's DO NOT try bending the cross arm while the engine is running. The fan will bite. At rest with the engine off the spring will not have tension on it. The B's had a stiff spring that is kind of hard to unhook, the C's and CA's had a dowel in the center to keep them hooked.

Thanks for the help though!