Tilt trim issue DT55

[dandog]

So a new second hand pump pump and can't get it to prime,....is there a sequence /process I need to follow to make the pump work? I had it partially working with air in the system but then discovered a pipe leak,fixed that ,then cant get it to even partially go again Any advice appreciated,,it's doing my head in.With all pipes off the pump,and full resovour it won't pump out fluid.....arrrrgh!