[Heathkit] SB200 SWR Meter

[Bruce Hudler WK3A]

Been working on a few SB200's lately and have a question on the SWR meter. Over the years I've not really paid any attention to them, as I guess we all have better things to measure with. 
The amp I'm working on seems to be not very accurate with the SWR on the antennas and the HN31 dummy load. It reads 1.5 to 1 on the dummy load. Even higher on antennas. 
This circuit and components are used in other stuff so I'm sure there are millions of them out there. 
Reworked the circuit with new 1N191 diodes, 100-ohm resistors ok, re centered the rods and measurements. No difference. Checked a couple of different bands, not much difference.
Not much there, maybe they are all that way  :) 
Any thoughts? Thanks

Bruce WK3A