I have my HPOP on the bench and suspect it is bad. The pump is from an 04 truck. I pulled the clip out of the backside of the pump and expected the guts to kind of fall out but they didnt. I also gently tapped it on the bench to see if it just needed some coaxing but that didnt help either. I searched this forum and didnt come up with anyone with info about taking them apart. I see pictures of them apart but not instructions on how to do so. My next thought was to pull the gear off the front side and maybe press it out through the backside. I am thinking there are some o rings in there that are holding everything together and they need a little help.
On some of the older pumps there is a ball bearing that is pressed into the case that pops out sometimes and causes a massive leak. I am not sure there are any parts inside you can fix. If it’s a swash plate piston pump, its time to replace it. Take photos for us to see. You might be the first one.