I'm in the process of converting a bike from Magura rim brakes to linear pulls. My question has to do with the hole for the return spring. My fork doesn't have any.
Instead it has a pair of 20 mm diameter, 5 mm thick (aluminum?) washers that are secured with set screws. The 2 mm return spring hole would have to be drilled 2.5 mm from the edge of the washer. I think that would be beyond my expertise. My low tech solution is to saw a kerf on one edge of the washer to retain the return spring nub.

My machinist son says "Bad idea." He's afraid the saw kerf might break out and I'd find myself coasting downhill on a rocky trail someday with no brakes. I'm thinking all the return spring nub does is to push the brake arm back when you release the brake. There is so little force involved it would be unlikely to break out and, even if it did, all that would happen is the brake would rub.

My son said he would machine me a proper pair of replacements but his time frame for doing (free) jobs like can be a LOT different than mine.

Are proper replacement parts get-able? If not, is my plan likely to cause me bodily harm?