Scoutmaster runs very slow

I have a Scoutmaster and the SDS. When I plug the Scoutmaster directly into the wall and measure speed with the KAB Speed Strobe 10 numbers drift by, moving right, in about 5 seconds. KAB states 10 numbers in one minute represents .3% accuraccy, so I'm really slow. Using the VPS, turned up to 66 frequency, 10 numbers drift by in around 15 seconds, better but still very slow. The voltage number reads 84. I would appreciate any suggestions