Congratulations!
So, when you lift on the arm in the back it does not move upwards?
I cannot see anything in the way from this shot.
Is the spring able to be moved up (compressed) by hand?
yes, the top piece of the compartment slides open. Try a drop or two of oil there too.
Good luck,
Steve
I would first try Oil, then try Tri-Flow, then try Kriol, then try Heat.