Question 1
when oil is hot oil pressure goes from 4 psi to 1 psi when I brake hard it is a known problem

Question 2
oil capacities
operator`s manual writes 5 (qts.) for 272 light duty and 6 (qts.) for 272 hevy duty, the 5 (qts.) I have filled do not come to top mark on oil dipstick
is it the pan or dipstick different from light and hevy

Question 3
have bought a new oil pump screen at Carpenter the small valve what function it has