Otk brake advice for a newb

Hi guys, getting my kart sorted as im using it soon. Checked my brakes and they don’t seem right.
Its an old otk evk chassis.
When pressed one piston moves really far and one moves considerably less, it seems to lock and i cant get it to move as far as the other. Even if you pump them a bit. I figured it needs bleeding so i tried to bleed it like a car brake keeping the reservoir topped up. Have done this before on my mates kart and it worked well. Anyway there’s almost no fluid coming out the nipple on the problem side.
I have a brake bleeding tool but the adpater doesnt screw into the reservoir, threads match up but look a little flat.
Is the problem me bleeding the wrong way? I popped the red boots off and they look like they could do with a rebuild. I habe removed the brake from the kart and plan to strip it for inspection.
Cheers evryone.

Here’s a link to a Power Republic YouTube video on bleeding brakes on a Tony kart. There are many others out there as well.
If bleeding doesn’t resolve this problem, you may have to rebuild the master cylinder and caliper.

Yea I had a watch of it, didnt realise it had to be done this way. Purely out of interest how come you cant bleed them like a car brake?
Im just gonna rebuild it anyway as its off the kart now. Caliper seems to move but I might do that as well as its off.