Okay I’ve done the test again properly this time, thanks for the pointers Marshall, these are the numbers: cylinder 1 - 200psi, cyl 2 -190 psi, cylinder 3 - 200 psi, cyl 4 - 200 psi, cyl 5 - 180 psi, cyl 6 - 200 psi, cyl 7 - 180 psi, cyl 8 - 200 psi. Any thoughts people?