Re the tension on the front brakes, do the canti studs have different holes to locate the tensioning springs? If they do then re-position the spring onto a different hole. Rotating it further away from the wheel will give you more tension. If there is only one hole then, err, new springs?
I'm pleased to say the Diablo is still going strong. We had our first lunchtime ride in the local woods today.
I never did get the front brakes working properly & the other set I bought were the same. It must be a 'master' spring issue. Anyway a set of new Shimano canti are now doing the job of slowing me down.
Someone has built some massive jumps in the woods. They must have massive balls as some of the ramps are 4/5 ft high & have landing pads about 8/10 ft away. I expect they aren't riding an early 90s steel bike!
I found the Shimano schematics very useful recently in exactly how the springs went on some slightly earlier cantis. This one is for the DX cantis. As you can see I think the longer tab on the spring goes into the plastic cover. If you get the orientation of the springs right as well as per the schematic you'll find that the triangular 'pointer' on the plastic cover lines-up with the marking on the back of the canti moulding depending on which hole you stick the small tab of the spring in - making it SLR or normal. Worth having a close look and then popping the original cantis back on?! https://si.shimano.com/pdfs/ev/EV-BR-M6 ... -1158G.pdf