I pulled my drives and second engine on Saturday, in preparation I lowered the drives from the transport position. The STB drive went down no problem, however the Port drive didn't want to drop all the way (the Port engine had already been removed, transmission was still installed). It would go so far then bypass, I cycled it up/down and few times and it dropped almost all the way. When I pulled the cylinders there was no mechanical interference preventing the drive from lowering. Could this be an air lock problem or pump issue? If I need to do a pump I'll do it now while the engines are out
Thanks Jason

Check your fluid level. My trs drives do the same thing because I have a small pin hole leak in one of the hoses.

Thanks I will check the lines and levels. Hopefully something simple like that!

Depending how old the cylinders are you might have internal shock pistons. The pistons have a habit of coming apart causing an internal leak, Later cylinders have solid pistons and don't normally have the problem.

Easiest way to check is:

1) With the rams disconnected from the drives see if you can get them both all the way retracted
2) disconnect the up hose at both rams
3) have someone hit the down button. If you have fluid coming out of the up port (remember the rams must be all the way down) you have a leak
4) re-connect hoses, trim up to extend both rams
5) disconnect down hoses at rams
6) hit the up button, if you have fluid coming out of the down port you have a leak

Excellent! Thank you for the troubleshooting guidance!

I finally got to disassembling the trim cylinders, they are the shock version.
Can the piston be changed to non-shock type?
Thanks Jason

Yes they can, and I see you already ordered them. Thank you for the order!

Thank you for the support, technically and as an advertiser on this site!