Saddle valve on water line to ice maker on fridge. DIY by my dad 40 some years ago? Can't seem to get valve closed… don't want to break and cause a mess.
Saddle valves: cheap, easy, and wrong
Saddle valve - Wikipedia
plumbing - Leaking saddle valve - Home Improvement Stack Exchange
How to replace a saddle valve for a refrigerator icemaker line? : r/Plumbing
Replacing a leaky saddle valve with a sharkbite stop with 1/4” compression fitting - YouTube
Replace a Saddle Valve in 5 Minutes to Fix, Repair Water Pipe Pin Valve - YouTube