From Lee: This may or may not be of some help.The open relays that are original equipment can be repaired if they're not too bad. Take a fingernail file or sand board and smooth the 'points' (contacts). You may be able to buy a point file at an auto store. Used to you could but I don't know whether they are available any more or not. I filed a lot of relay points on the old IBM punch card machines.
My immediate need is to replace the relays. I have 1 failed and another on
its way out. Is there a modern equivalent? The one that failed is the one that cuts power when the brake is applied -- I have it jury-rigged in a bad way. The one that is failing I'm not quite sure yet, but to be on the safe side, I wouldjust replace all of them.