I'll admit it... I've never soldered anything in my life. So, to
replace a corroded, leaky copper elbow joint, my father-in-law
instructed me to heat the pipe, pull off the old joint, then replace
it... after proper preparation, of course.

The problem is that I heated the old elbow, but nothing happened. I
heated the pipe & the elbow... nothing. Couldn't get it off.

Any suggestions would be greatly appreciated, as I dread the cost of
having a plumber do what seems to be a simple replacement.