I am slowly restoring a 1963 220S and having a great time. I love the problem solving. Here's my currant quandary. On long hills (going up) I do fine if I have a lot of momentum (55 mph) but there is this one hill I have to navigate daily that causes problems. I hit the first gradient rise at 40 mpg, continue to accelerate to 45 when the gradient increases again. (This is a very steep hill, 3/4 mile long with a truck run-away ramp.) The car has an automatic transmission and it is in third gear at this point. Slowly and gradually I lose speed until the summit when I am down to 20 mph. The gearing doesn't shift down to second gear until about 17 mph. The kick down switch under the gas pedal does not work. I can manually shift into a lower gear but I hate to do this (gotta baby the old automatic.)

What could be to blame for this?

The car has 87k miles and was a barn find that was traded a couple of times before any real miles were put on it by me.

Thanks for your ideas,
David