Partial solution to the Geyers. (I’m not taking much credit, used the hint from the rumour shop):
The next geyser to erupt is the one that starts with the letter with which the current geyser ends. If Chirtoff erupts, you need to type F. And so on. This doesn’t always work, so there must be an additional trick. But is works often enough to be useful.
Solution to the Printle Factory
Everything that starts with ‘metal’ must be Tightened, everything else must be Drilled.
Not quite the solution to the Spa
I thought it was this: go from the shortest activity to the longest, in terms of number of letters. But it doesn’t always work.