There is only one consistently safe way to pull Alps tee mount keycaps. You should not attempt anything else, as plastics involved can be quite brittle/old, or in the case of DCS keycaps the mold can sometimes lack supports.
Use a high-quality wire keycap puller only. The weirdly shaped ones that come with some cheaper Chinese keyboards aren’t a good shape for pulling Alps caps. Plastic ring-type pullers should not be used due to likelihood of breaking or scratching keycaps. Get a good grip around the keycap with the wire puller and pull straight up. Do not wiggle, tease, rock side-to-side or impart any lateral movement at all. If the keycap has a death grip, continue pulling straight up and simply apply more force until the keycap releases.
The best way to fix an unhappy contact module will always be replacement with a better one - but there are some easy tricks to try if a switch has recently died or isn't working after a while in storage. As a first port of call, you should try pressing down very hard on the key and wiggling in a north-south direction. If the switch is chattering, do this until the switch is outputting one character on every north wiggle. If it wasn't registering, wiggle until it does.
This has been tested on Alps SKCM, SKCL, SKCC and SKFL. It really works. Restoration is significant. If the switches are only a bit bad, you will get top tier results. If they're super bad, they will become very usable.
Instructions
For further information, check out the Waxboil FAQ.