Thinking about some of the easy things to eliminate - check: the fuel tank breather for any blockage, the exhaust elbow for any soot/crud build up, exhaust pipe for crud/delamination.
My advice, particularly if you buy a budget band saw, is to can the budget blade supplied with it. Get a set of decent blades from Ian at Tuffsaws. Tuff Saws. . If you don't know what you want chat with him and he will advise. A lot of the pro woodworkers and more serious DIYers buy their...
"Massie's book 'Dreadnought' is a good intro and for JB, Johnston's 'Ships for a Nation' is a good start."
I would also recommend Massie's 'Castles of Steel' Both tomes are excellent reads.
If you decide to re rig and are not too worried about whether it's shiny or not maybe consider galvanised rigging? By not going through a marine supplier it's a cheap as chips and possibly longer lifed than stainless. I've used these guys Rope Assemblies - Welcome to Rope Assemblies Ltd . Next...
Perhaps invest in a sculling oar that you could steer with?
Trouble with hydraulic oil is that a little spreads a long way when it seeps out of that breather! Use of the helm and autohelm may force the little bit of remaining air out of the system. How much fluid is collecting in the drip tray...
Frank
I had a similar experience with a Vetus pump. As has been suggested your problem is down to air in the system. Bleeding is a 2 person job and instructions are on the net. You can tell if there is remaining air in the system as the helm will feel ‘spongey’ at full lock (either). If still...