I should probably get a replacement switch or two for my GK.
As an FYI, I've had great luck with the CRC QD Electrical Contact Cleaner. It's an aerosol can, and typically in stock at Home Depot. I've used it on my GK buttons - my Deal button was so bad it didn't work when I bought the machine. Turned the machine off, popped the button cap off, did a liberal spray, and worked the button several times. Reinstalled the cap, and it's working again. No, it's not like new - it's still worn, but it did bring back to life a button/switch from non-working to working 90% of the time (aka, having to press it a second time). Have also used the electrical contact cleaner on other projects - my 4-way mirror button on my vehicle, a noisy potentiometer on a project, etc.
I also ended up replacing my button bulbs with LED. Tried to find ones that weren't too bright, am currently using these (which are 12vdc, so directional when replacing);
https://www.amazon.com/gp/product/B016FKOGQW