TRX-4 2065 Servo Spring Horn Jig

My TRX-4 shift servo broke and I had to swap the spring loaded horn to a new servo. That did NOT go well. I broke the new servo instantly because I found out then you have to keep pressure on the top and the spring makes this almost impossible by hand
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Well there's no convenient way to keep pressure on the top. I use a pair of vice grips which worked but you can only hold a small corner and it's kinda difficult.

SO I built this jig to hold the center section of the horn down and there's a