standing skull crushers are horrible on my elbows and have been since high school. laying on a flat bench doing the same movement with an ez bar curl is much better for me. however I usually do this instead:
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the X's are various places I will try to set the pin to change where the cable pull is coming from. usually that middle x is my sweet spot where I get a massive stretch on the tricep. I use the rope attachment instead of a solid bar attachment because it lets my hands change the shape of the rom a little to accomodate the elbows and still get a gnarly tricep pump. your new machine might let you figure out a variation of this....
when my elbows are flaring up I'll do a ton of light db work and it really seems to help a LOT after a couple weeks. I'm convinced my elbow issues are typically from GRIP more than anything. so lots of deadlifts can leave elbows sore about twice a year for a few weeks.