I learned that 90% of my fixes go like this:
Figure out the problem. Order a new part. Wait a week or so for it to come in (all the while a machine is down). Find free time to make the fix. Discover that my "fix" did nothing to change anything. Reassess the problem. Realize I was wrong, and that it only needs a small tweak somewhere. After hours (really weeks) of work, fix the problem in about 2 minutes with stuff I already had on hand. End up with more spare parts. Then I try to pretend my pride in fixing something overshadows the dumbness in which I went about it.
Repeat ad infinitum.