I have a car that the engine cover release is stuck, pull knob doesn’t move at all. previous owner rigged a release cable through the engine grate. I would like to try and replace stuck factory cable, any recommendations on how to go about this?

I'd start by looking to pop it open through the trunk first and then assess what the problem is.

This is a very simple mechanism, it's most likely gummed up from dried up gunk inside of it.

Get it open, let the cable loose, un-bolt the latch out and soak it in gasoline or solvent. Then, re-grease it, it should work freely.

Thank you for the quick reply Larmo. I can open it with the rigged up cable. But once open, the tube itself seems to be rusted solid? I will try to get a bunch of pb blaster in there to see if it loosens up. If I can get it out, do any of you use a silicone spray or anything on the new cable?

Just a couple days ago, I discovered my engine cable tube was gunked up when I went to install the cable. I ran a coat hanger through it to clear it out (turned out it was full of blasting media). I'm going to pick up a set of tube brushes next time I'm at Harbor Freight to give it a more thorough scrubbing and then run some teflon dry lube inside more just to coat and protect the tube than to provide lubrication, but it should do both.