This 750 has been sitting for 20 years or so and the front brake needed pretty much everything replaced. I rebuilt the master cylinder, caliper. Replaced hoses, built a new steel line, put on stainless banjo bolts. I started the brake-bleeding adventure and there was a serious leak at the brake-line connection to the caliper. looked in the hole and the little 'tit' at the bottom looked a tad deformed......no, very deformed. It looked like steel so i reckoned it must've been pressed in. With nothing to lose, I decided to get it out. I had a spare caliper I'd picked up on ebay but it was pretty beat up - but the seat looked good. Anyhow, I managed to remove the seat with a tool made from a nail. I found the fattest construction-type nail that would just fit into the seat and cut it to length so it'd fit in the caliper bore. Then I ground down the nail head 'til it would just fit through the hole in the aluminum bore leading to the seat. With the nail inserted from the bore side of the seat, I clamped the end of the nail in a vise leaving some space between the jaws and the caliper - enough to stick in a pry-bar and a wooden wedge to protect the aluminum. It took quite a bit of force, but the bastard came out. It was a mess. I chucked it in my drill-press and with it spinning, ran a file down the destroyed chamfer that's supposed to form a seal with the brake line. Then, with the part still spinning, I buffed it up with some silicon-carbide paper on a wood block. I went through the same operation with the seat from the spare caliper. I pressed the seat back in by lubing everything up with brake-lube and then screwing down a fitting to push the seat into place. No more leaks and I have a spare seat.
Hope this description isn't too convoluted.
