A few things. When checking balance, you should also reverse the blade 180 degrees to see if the drop reverses as well. This is simply a step to assure your actions. If your pivot is too big in diameter, it can create enough friction with the blade to alter a true reading of balance.
Biggest issue with grinders is heat. Avoid creating too much heat as it will alter tempor. I keep a 5 gallon pail of water ready as a heat sink.
As for the thread locker, there is usually no need to clean the old off. Simply add a fresh drop or two near the tip and it will spread as you thread it into place. If it still looks well coated and you can feel it, might not need to add any. Your call. In the USA, threadlocker has gone up 300-500 percent in cost over the past 5 years.
Great job Ken.