Can someone define what parts make up the "Action Center" in a Grand please?

Thank you

There's no one "Action Center", Mark. The action centers are the pinned joints, i.e., flange to hammershank, flange to wippen, etc.

That was my thought.
But I had a (cowboy?) technician tell me that if I lubed the action center "joint" on a grand, it would decrease it's touchweight...

Thank you for clarifying...

Run away run away!!!

There's so much more to touchweight than that (and I'm certainly no expert). The centers need their proper amount of friction. If they're tight, they need proper sizing or repinning. Not a big fan of "lube"...

Actually,
I did some careful measurements on this, and in the most impressive cases, I found that putting CLP on the hammer shank action centres reduced the friction (DW-UP/2) by up to 15g.

It just depends on what condition the instrument is in the first place!

If you're concerned about touchweight, check all sources of friction, polish pins and capstans, check whippen heel felt etc, BEFORE you do anything drastic like adding weights etc.

ps: I'm only an amateur tech, but I doubt anyone will disagree with what I've said...(flameproof suit time?)

Also...
CLP isn't what you're thinking of as 'lube'. It's a synthetic chemical which cleans oxide and dirt of the pins. The only lubricant I have ever used is talcum power and teflon powder on knuckles and key bushings.

I have seen some people suggest other actual liquid lubricants but personally I would NOT do this ever. (someone here uses a bio-oil for gun barrels for example).

As JDelmore said, there's a lot more to downweight than friction. However, if the instrument used to be fine, then increased friction could well be the cause.

Thank you, all !

Sometimes it's a mistake to get technical. He probably calls it that because you can get into long detailed explnations that won't make any real sense to the client anyway. So he might just call all the moving parts, the action center. It is so wrong to jump all over a person because they used a generalized explanation. He had the problem right. The friction needs to be dealt with and the DW will come down.