If you don't have 110 you will not have weld. Check the 2 brushes under the nose cone, clean the slip rings (brass rings the brushes ride on). Check the wiring, you could have faulty connections or mouse chewed wires. Have you taken the metal 'wrapper' off of the generator housing (it has 2 screws that hold it together and it wraps around your generator housing), and checked your main brushes and wiring in there?
If you have a volt/ohm meter you can check the voltage across the exciter brushholders. With the fine current control set at 100, put one meter lead on screw stud of the right exciter brush holder, put the other meter lead on the screw stud of the left brush holder. You should read 110 volts DC.
Other than that just check your wiring and component condition.