[Bill R]

Are the degauss coils around the face of the tube ok? If they are use them to degauss the tube. You should be able to umplug them from the chassis and apply 120volts ac to them directly. I would use a variac so the voltage could be lowered to the coils and they do not shut off all at once. The thermister works by directing ac to the coils when cold then as it heats up it usually acts as a short so no current flows in the coils. If they are in series with the coils the resistance increases as they get hot and current doesn't flow through the coils.
I usually start by degaussing the set, then I get the static center convergence as close as possible, set the purity, repeat if necessary, then I do the dynamic convergence. Oh yeah repeat as necessary. It doesn't always come together the first time, but each time will get easier. It is also a good idea if you have the sams to follow the dynamic convergence instructions in the sequence they are given. Just turning the controls at random may make it harder to converge.