Have an SB-200. For some reason, just idling the HV voltage is fluctuating rather significantly. Within the space of a few seconds, it drops from 2100 V down to 1800 V or so, and then goes back up. It seems to be jumping around in the range [1800, 2200]. What would cause this, and is it a sign of problems? Note: I just replaced the three 4.7 M resistors and the 15K resistor.