W123

Not really a do-it-myself'er, but figured I'd check in for some help/advice.

My engine has 149,000 miles and I've owned it for the past 40,000.

This morning, I was backing out of my parking spot and was having trouble shifting into reverse. Put it in 1st and it then shifted smoothly into reverse. Didn't experience and problems driving 10 miles to work.

I'm hoping someone can readily identify this issue before I have to break down and shell out for a mechanic due to the urgency of getting it resolved... My ASTM-certified-biodiesel powered 1982 W123 300D-T is having issues with starting up first thing in the morning. It has gotten bad over the past couple of weeks to the point where it won't always fire up on the first try or two. When it does catch, it "chugs" really hard, smokes light-to-medium gray like a chimney and generally sounds grumpy for a bit before smoothing out.

I am having trouble with the A/C compressor on my 1984 300D.
It appears that there were several hose-block connections and compressor connection configurations.
I ordered a new compressor (for a different car). It came with the adapters and instructions. Unfortunelty, I'm having trouble understanding them.
I can't get the compressor to stop leaking at the hose connections in the rear.