The old pull-release Marlens are amazing machines, but they require careful setting up as far as spring-tensions, pedal and lever travel, lever return-springs etc are concerned. The tuning is intuitive once you understand how the pull-release system works.
I took a Marlen pull release which had rods which were just a tad crowded, like this:-
and managed to turn it into this:-
with all the rods essentially parallel, none binding and all the pulls as straight as possible.
It took quite a bit of work making double-sided bellcranks, threading pull-rods, making stop-collars and rod-clamps, engineering a reversing-mechanism for the E-lowers, but the end result was well worth it.
Richard Burton is inspiring with his engineering and diagrams. Check some of his Youtube playing on his Marlen to get an idea of just how good these old steels can sound.
The steel guitar is a hard mistress. She will obsess you, bemuse and bewitch you. She will dash your hopes on what seems to be whim, only to tease you into renewing the relationship once more so she can do it to you all over again...and yet, if you somehow manage to touch her in that certain magic way, she will yield up a sound which has so much soul, raw emotion and heartfelt depth to it that she will pierce you to the very core of your being.