The black plastic 'thingie' you are talking about would be the bit that
snaps over the ball 'thingie' fitted to the tiller, yes?
I would imagine there might have been some thread locking fluid used to
stop it undoing all by itself. I have never had mine unscrewed so I
cannot say how hard it was to undo.
Using vice grips on the push rod would not be a good idea, even with
something wrapped around the jaws.
I would get two pieces of wood, clamp them together with a piece of
cardboard in between, drill a hole the size of the rod through the centre
and then use the resulting half rounds to clamp the rod securely in a
vice with little chance of damaging it. Similar clamping and a G clamp
for the plastic thingie should get it undone.
Klaus

lgcharlot wrote:

I just received my Simrad TP20, to be installed on a Catalina 25.
Having been advised that my boat would require the 150 mm pushrod
extension, I ordered it, and it arrived separately. The pushrod looks
like it is threaded both ends, and is pretty obviously intended to go
between the primary pushrod and the black plastic fitting on the tip
of the pushrod. My problem is, I can't seem to unscrew the black
plastic fitting by hand. I don't want to use tools and risk damaging
it. Is this black plastic thingy supposed to be so hard to unscrew?
Is it okay to take a pliers or Vise Grip to it as long as I am
relatively gentle about it?