Two hydraulic problems

[Rimrock]

A possibility is that there could be some obstruction in one, or several of the fittings/channels leading from the fittings into the cylinder barrel. Another possibility is internal leaks in the piston O-rings (which will wear over time). But if it's been like this all time, the O-rings might be okay, as the other cylinders work okay. So I would possible dismantled the cylinders from the machine and checked the fittings/channels for obstructions. Maybe something is not 'in-line' and causes a obstruction.
Regarding the pump, if it's an early Magom product, it just 'enjoys' running hot...15-20K rpm, foaming and 'boiling' oil..Possible helps to reduce the pressure setting. Newer pumps with brushless motors seams to have been upgraded to perform better and last longer.