128 lift handle detent pin/ button help

[Steveshow]

I have a 1973 128 that was passed down to me by my dad. He got it from my uncle, his brother. I believe he bought it new. It came with a tiller attachment, but the story always was that it was never used, as the ground speed of the tractor was too fast, and it was too heavy to lift. (The paint wasn't even worn off the tines when I reinstalled it!) I sure wish he would have bought a 129 hydro with electric lift...With guidance from this site a couple of years ago, I sourced and installed a creeper box and a lift spring assist. Now I nee help disassembling the lift arm, as the pin/ button that extends out of the handle has been broken off for as long as I can remember. We used a stubby screwdriver inserted from the top to engage the detent in order to raise and lower the mower deck, but that set up gets a little complicated with the heavier tiller. I bought a new pin, but before I go ham fisted tearing into the handle, I thought I would ask for some guidance.