I have got one second hand oil pump for 50$. And it is still good according to next test:
I could not insert measuring feeler gauge of 0,003 and 0,002 was going hardly.
Corresponding to data (minimal lover and maximal upper value) in red elipse below i am OK.
My old pump did failed all tests.
(A:”Do you want one beer?” B: “No i am OK.” A: “So what?! You are telling that i am not Ok?”)