You could rock up to an auto mechanic and see if they can fish out a two arm gear puller for you, but depending on the shape of your crank you might struggle to get a grip.
Sometimes it is just their time to go. I have tried a gear puller before after all sorts of sh*t, ended up bending the spider arms, I was careful and even had a crude backing plate at the base of the arms (if you attach the puller to the chainring holes or edge of the spider you will bend the tabs for sure). I finally had a gutfull and got nasty, ground out a big slot between spider arms and bashed it off. These were old 105 cranks though, likely to be made from a poorer and softer alloy (more likely to bend and bind) than your 75’s.
Would a 3-arm crank puller be better because it spreads the load better? Apart from that, a couple of flat steel plates maybe 3mm thick shaped to fit behind the arms as close to the centre as possible would be the most careful you could be.
I wouldn’t give up on it - plan to have someone put a thread insert in for you, and for it to cost $30 or so. The kit to put it in would be several times that, and you’ll hopefully never need it again.
I’m sure most people learn by breaking things - I know I have! I have done this by mis-threading the removal tool in, and by trying to remove the crank without taking the bolt out first. Doh!
I tihnk he means to get someone to insert a heli coil into the crank when you get it off; it’s a steel thread that is tapped into the crank to replace the stripped thread. they work pretty well
Putting torque on a loose square taper rounds it off. Once it rounds off it’s terminal and time for a crank replacement. People complain how square taper is shit because they didn’t check for loosening, rounded the taper once and subsequent tightening results in a short term grip which quickly loosens, they tighten more and something cracks.
A three arm crank puller wont be able to grab the crank itself, you’d prob have to grab the chainring which will promptly bend and piss you off even more.
