Hi Tony:

I do not have a good answer for you, but do have a couple of suggestions.

1. Do not assume that because a magnet used by the same company decades
earlier is good, that the magnet made later is also good. Often, in
production, later manufacturing methods are developed to save money. I have
also seen where production methods are changed and for a few years, the
material has limited lifespan, then the company converts back to the
original method.

2. Check to determine if the same lack of sensitivity occurs at the low end
of the meter. If not, that might indicate a mechanical drag.

3. I salute your willingness to explore new areas of restoration, but make
sure, before you operate, that you have the right organ.

73, Colin K7FM