Tonearm Question (Picture Inside)

So I'm still kind of a turntable noob, but I'm slowly learning... I picked up a couple of second hand Technics 1210 mk2s, and I noticed that the tonearms on them are slightly different. The picture I have enclosed is on the one that looks like it is not stock. The problem is that it results in me having to put the counterweight much closer to the base of the tonearm than I do on the other table. I go through the motions of putting the counterweight such that its weightless and zeroed. Then I set the weight accordingly for my cartridge (I'm using m44-7's so I set it to 1.5, is that correct?). But the weight is set so close to the base as you will see that even though I believe it's set correctly it still sounds like I'm putting too much weight on my records. It certainly sounds distorted relative to the other deck, or at least much louder.

Is this something I should replace or am I missing an added part of the counterweight stub? I've never had them properly serviced but I checked them over when I bought them using one of the guides I found here and everything seemed to be working properly... I hadn't even noticed the difference in the tonearms til now to be quite honest.
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