I needed to rebuild the rudder bearings. Stripping the old ones out of the rudder tube was not difficult, but there was not much of them left. Measuring the new rudder shaft told me everything I thought I needed to know. I machined up the bearings form Vesconite and, in a fit of "intelligent design" decided to make the bearing surface greater (why not, I already had the vesconite slug, why not use most of it?)
Anyway...Made the bits up, fitted them to the shaft and found everything rotated nice and smoothly, took them to the boat and installed them into the tube. Then it came time to install the rudder and it was not easy....But in the end it was in place and.....Took about 6kg or more of force to swing from side to side?!?!?
Turns out the rudder tube (which is after all only a length of copper pipe that had been glassed over) was not perfectly straight...The 1inch solid stainless rudder shaft WAS....This meant the bearings were sitting at a bit of an angle to the shaft and were acting as brakes. The reason the old bearings were so crushed and crumbled when we removed them became clear.
I thought about the ten possible ways to fix the problem (we had about three hours left on the slip)....None of the PROPER methods would fit the bill....So I dropped the rudder as much as possible so that some bit of the shaft still projected above the deck. I checked that the rudder could, in this possition spin a complete 360...and then I attached an electric drill to the top of the shaft. Ten minutes clockwise, ten minutes anti-clockwise (I think five would have done, honestly). The drill was a slow, hi-torque thing mostly used for it's jackhammering ability...But it certainly did the trick and loosened the rudder up in the limited time we had. It now works perfectly and has no knocking, rattling or other "issues" at all.
The first one was the whoops example you asked for...The way we fixed it was the "getting away with it".