Comparing the old and new horseshoes, is it the same? If it's the same, that's fine. The key is how to adjust, tighten the brake line, not very tight, and then adjust the adjusting screw on the top of the brake. You can try left and right to see if there is that point. If you find that point (when the wheels are running freely), it won't be tight. Tighten the brake line again, then adjust the adjusting screw and repeat it several times. What the mechanic said is wrong. If you ran in, the battery would have been dead or damaged.