Welcome aboard!
That helm that won't respond is LOW on fluid.
CHECKING TELEFLEX SEASTAR FLUID LEVEL:
Per the Teleflex/Sea Star manual, if the helm is mounted horizontal (+/- 20 degrees) the fluid should be at the bottom of the threads in that fill port. If mounted vertical (+/- 20 degrees) the fluid should be 1/2" below the bottom thread.
It is not uncommon to have to top off a helm unit every once in a while, but some units won't need it at all during the season. I find units left "hard over w/ the OB trimmed up" may weep a bit out of the steering arm seals, which might exit/drip overboard, so you may never notice it.
Try this, bring fluid up to proper level referred to, then turn wheel hard over one way. With the fill port cap open, keep turning the wheel hard, then release the wheel, and repeat ... while watching the fluid level. If it "drops" when you apply turning force there is air in the system which you could bleed out. Repeat this test by turning the wheel hard over the other way. Tip: Never turn the wheel with the vent cap open and always open a vent cap SLOWLY (and 'rock' it in the threads without completely removing it).