[Boatanchors] Hickok Tube Tester Meters?

[W4QG]

Hello All,

Please forgive the post (boatanchor test equipment) -
I will be using it to work on boatanchor radios however.

I am considering repairing a Hickok 533A tester I recently 
acquired as part of a package deal. The tester is in reasonably 
good condition except the meter is missing. 
I have checked around and the exact replacement meters for
this tester are somewhat pricey ($100-$150).

I do have access to a Hickok 550 meter that is working.
However, the its size is larger than the original 533A meter and
apparently does not have the same input requirements. 
Looks like it is deflecting about 33% of scale from where is should 
be. My first thought would be to strap a resistor across the
meter terminals to lower the input resistance. I have looked everywhere
trying to find the specs on these meters with no luck, anyone have any
suggestions?

Thanks!

73,

Paul W4QG