Anyone ever open up their PA900?

Mine is 3 years old, and has been lovingly played, almost every night during that time, for 3-5 hours a night. It may be time to replace the key contacts before they go ka-boom. (There's signs of irregularity popping up)

My thought is this:

I wonder if I can upgrade the springs to get a stiffer action, more like the PA4x. I called Korg support, and they're looking into it, but I wanted to ask here. Some of you might have done a similar repair/mod yourselves? maybe?
Replacing the contacts is easy (time consuming, but simple), and I hope replacing the springs is just as easy when it's opened up.

I'd be thrilled if I could get stronger springs, or maybe key weights to bolster up the action. This is my road rig, and it needs to be tested tough.
(Wish Ford made keyboards!)

Weigh in please ... if you've had experience in this. (Donny - no video links, please)
I'm looking for advice from end users who've dome similar operations ... that I trust.

dave I would think it can be done somehow...just take out one of the key springs and go to an online spring manufacturer company and see if you could find the exact same springs in a little thicker gage and replace
or try to find out what spring is being used in the Pa4x also...
good luck keep us posted..