A. It doesn't work right.

B. That means it's broken.

C. As my A-school Chief taught us; God hates cowards. let's try to fix it.

D. Trim the spring a half-turn at a time. That will release pressure on the make-shift ball check valve.

E. By the time you cut a couple of turns off, you should see some reduction in oil pressure. If not - oops, look elsewhere. Keep looking for a different pump. Even a junk one should have a spring and plunger.

And, I heartily agree - look at the oil for metal flakes. Engines should not make metal. That's why aircraft engines and helicopter transmissions have chip lights (magnetic metal detectors) to keep track of stuff like that in the oil. A couple of years ago, FiFi, the CAF B-29, had to sit for a year because two of those gawd-awful huge radial engines started to make metal.