I'd just get a better indicator. In a test I did a few years ago of a Mitutoyo indicator,a Last Word,and a plunger back Starrett I have in new condition,the plunger back took by far the most force to move the needle. Just inherent in the design.
I tested them by pressing their feelers or plungers against a very sensitive digital diamond weighing scale we have for my wife's jewelry business. I checked how much(in grams)the scale registered to move the indicator .001". The plunger back was much the least sensitive. This means that you are less likely to get the most accurate response from it in actual use. I can't recall the numbers by now,but I certainly recall the order of least sensitivity of the indicators tested.
Somewhere in this site,my post still remains if you might do a search for it.
The Mitutoyo was BY VERY FAR the most sensitive. You really want the most sensitive one. Also,the long,thin feeler of the Mitutoyo can much more easily be gotten into difficult or impossible places that the plunger back just cannot reach.
Many years ago,when I was starting out,I used a plunger back,but have long since moved on.