Recently I had a revolver come into the shop. It was to be a fairly easy refinish from the normal satin / brushed metal finish which is pretty standard on most stainless steel revolvers, to a mirror high polish finish, with some refinishing of the rosewood grips as well.
Disassembly was mostly easy, aside from the base pin being a bit of a pain to take out, though I had attributed this to just being dry metal and having no lubrication to help it move smoothly.
The refinish went off flawlessly, and only took me a couple of hours to complete. When it came time for reassembly, I noticed I was still having a hell of a time putting in the base pin for the cylinder- it would not install smoothly even with a good oil, or a non liquid lubricant like molybdenum powder.
Once in, I also noticed that it no longer was effective in moving the transfer bar out of the way as it should. With the cylinder removed, it worked just fine. Something, I deduced, wasn't working quite right.
So I checked to see whether or not the base pin was bent. Rolling it on the flat surface of my work area, I noticed the tiniest little bit of light was able to shine under when I rolled the pin, while other areas would not let light through at all. I followed up with a measuring tool and found that sure enough, the pin was not straight, which would also account for it's inability to work properly when installed with the cylinder. A new part was promptly ordered.
Once installed, I'll do the same checks to make sure the new part is true.
It just goes to show that the smallest problem with one part, can cause a cascade effect which renders the other parts inoperable as well.
A little diagnostic work went a long way (in this case) towards saving a bigger expense of replacing other parts which were not the culprit.