[Amps] Line voltage high.

[Ken Durand]

Hi group, I checked the filament voltage on my FL2100b and it is at 7.2
volts or there about. So I then checked the line voltage going to the amp
and it is 257 vac, the amp was built for 220v. The HV is at 2500v. What
would be the best way of reducing the filament voltage down to 6.3 volts?
The HV is still within the tube voltage ratings. I don't have a 240 v
variac. 

Ken