Grimrock

In the teleporter puzzle I can only find onde secret button. And after pressing it nothing seems to happen. Then, I cannot find the second ore and cannot carry on. Need a more specific clue.

The secret button does change something in the teleporter room, but the change gets reverted whenever you are teleported out of this room so try as hard as you can to stay in there and explore what changed. Save/Load can help with this.

if you get snagged by the teleporter (taken back out of the room) - both secret doors will close. The first secret button is in plain view.... and sounds like you can get to it ok
run out from the middle cage area, step left - press the first button - then take 2 steps right - that teleport position will take you back within the cage area and face you so you see the secret door openning.
Once you hit up the first chest, there is another secret button hidden by some vines... press it and when you step out into the teleport area again - take 2 steps right (get teleported) and then immediately continue with 3 steps right (and get teleported again).... this will take you back into the cage area, from there you should be able to navigate to the other secret door via the same way you succeeded in pressing the first secret button.

1. I think you should give a hint for the ore i.e. the door mechanism needs fuel to operate or something. I thought I had to cast certain spells into the receptors or maybe there is a demon head behind a hidden wall that activates them. If you had not told me I don't know if I had tried to put ore into them.
2. The red gem - I think there should be a hint to take it with you. At least the first time. I left it behind because when I took it with me the gate closed to the spiders and then teleport area, so I thought it has to be left in the alcove
3. If you have not done so already, please check all the wisp shift locations for errors i.e. unwanted locations. I teleported myself into a closed holding cell Yeah no way out - reload. I cannot remember right now but there were other locations too where I thought it might not be correct to be able to wisp shift into this area. As this feeling occurs quite often I suggest you check all of them. As a player I will try out every possible direction because I don't know where the secret is hiding

It is possible to get stuck in the puzzle I was having trouble. If you put an item on one of the plates, get to the corridor and then you hit the "wrong place" to teleport, you'll be stuck in the cages with no way out!

one of my fighters is alreay with 50 in unarmed combat, but even him can't equip the pit fighter glove. Seems you changed something else other than the name of the item

I agree and will definitely be making a wall text with another "lie" about the ore and receptors. There really was no clue for that at all. Thanks

You're very right there... The red (and other) gem puzzles were some of my first, the clues are very cryptic and not very obvious. I think I will "upgrade" those puzzles with different wording with the clues.

I had encountered a couple of mistakes with the wisp shift locations very early on. I will be checking every location for "secret only" shifts - no shifting into the Grand Staircase and no shifting into closed holding cells