Old Invader Master Cylinder Rebuild?

Any help would be greatly appreciated. I would like some help finding parts to rebuild a mid to late 90s Invader branded master cylinder and caliper. I recently bought an invader pro works kart from the mid to late 90s. I need to rebuild the master cylinder for the brakes because stuff is getting in the brake fluid. Does anyone know where to find parts for these older Invader branded hydraulic brakes? Thank you

Edit - I should add that when I bought the kart it had been sitting for a long time so the brake fluid was absolutely disgusting when I drained it.

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Pics would help. I thought they used MCPs.

Alright, I added some pictures now.

I have the same brakes from my Invader. The master cylinder is easy, it’s a MCP (just a Invader cover). The caliper is the tough one. Invader made these (or had them made) I couldn’t find replacement pads, and the pad adjustment screws/seals are a pain, and trouble prone for sealing/air leaks. In the end I was able to rebuild and get the system to work (plenty of pad life), but I replaced the entire system for reliability reasons.

You could reach out to Cole Nelson, Gary Nelson’s son. Gary and friends started the Invader brand.

I kept the original system for resale with the chassis when it’s time. The chassis is a 98 - 99ish.

Thank you so much. I will contact Cole Nelson and see what he says about the brake caliper.