We got the ATV back from the shop last week and
it's better, but not quite fixed.
The problem was no brakes. We
had the back pads replaced and made sure the front pads had enough life
in them.
It slows down, but I have to
pump the brake handle and be careful not to hit anything. I think maybe
the caliper got damaged and we may have to plan on having it replaced
in the future, but for now we'll get by with half brakes so we can get
caught up on manure hauling.
Calipers don't break easily. The only moving parts (pistons) are inside facing the brake disk. Practically the only thing that can break inside are the seals. If the brakes squeel a lot, they could be leaking brake fluid. Do you notice a change of the brake fluid level in the reservoir over time?
If the brakes feel soft, the first thing to look at are air bubbles in the hydraulic lines. Even a tiny bubble makes the brakes feel very soft. You have to bleed the brakes to fix that. You can do that yourself but be careful with brake fluid. It is aggressive. Open the bleed nipple on the caliper and put a transparent hose on it the leads to a container to capture the fluid. Also open the brake fluid reservoir and top it off with the correct brake fluid. Use the handle or lever to pump oil through the system. Watch the hose on the bleed nipple to see if any air bubbles come out with the fluid. Close the bleed nipple and see if the brake is firm now. It not, keep bleeding.
The second thing is a small oil leak, e.g. caused by a damaged hydraulic line or seal. This will probably be difficult to spot. This leak can also be in the pump connected to the brake handle or lever, probably a broken seal. In the latter case it needs to be rebuilt or exchanged. Best leave that to a repair shop.