I have a Coleman 220F lantern from January 1971, I disassembled it and cleaned it, I managed to start it, but I noticed a problem - fuel is getting into the pump chamber through the check valve, I turned the check valve and there is a small hole under it, I don't know if it should be there to be or not?
Check Valve probably needs to be replaced because it lets air through when the air stem is turned off.
Sorry for mistakes, but I don't know English well.
Now, to troubleshoot the check valve, first, with the check valve out of the fount, shake it to see whether the ball in the valve rattles. If it does, fine, but if not, you'll need to free it up. To free up the ball, soak the check valve in a solvent for a while (I use alcohol), and poke the ball periodically with a bamboo skewer or something similar. Work at it until the ball rattles freely in the check valve. Reinstall the check valve, and with luck, it will work just fine. What I do to check for a leaky check valve/air stem, is pressurize the fount, close the air stem, remove the plunger and pour a few drops of alcohol into the pump tube. If it bubbles, you have a leak and you'll have to decide whether to replace the check valve/air stem.
Your English is just fine!
If the snorkel tube and the pump housing are not damaged, then you normally should not be getting any fuel coming into the pump tube. If the check valve is still removed, empty any fuel out of the pump tube, refill the lantern to the fill port, then observe the pump tube for fuel ingress into the pump tube over a couple of hours. If fuel stars filling the tube, then there is probably a crack or hole in the lower pump assembly. If the check valve is installed, fill the lantern, pump it up, ensure the pump needle valve is closed, remove the pump plunger assembly, then monitor for fuel ingress into the pump tube. If there is no fuel leakage into the pump tube, then the pump assembly is probably generally useable. If there is no fuel leakage, you can also put some fuel in the pump tube and check for air leakage (bubbling) around the pump needle valve or around the check valve threads.
I will try to clean the check valve and see if it works.