Starting problem 76 115 300D

[StolenBaby]

I've posted once before about my 115 300D here on this forum, but here's just a tiny backstory- I bartered for the car with a 72 Ludwig drumset, and my intention is to get it running well for at least 2 or 3 more years of solid driving.

However, after I drove it back to my place (a real crawl- 15mph max uphill), it refused to turn over. I got some cranking and some smoke out the back (greyish/whitish smoke- burning oil, no?), and a couple of times I thought it was going to catch, but it never did. With the second try, I only got the click of the solenoid (and please correct me if I'm wrong- I'm a complete novice). Since the car had not been driven very much previously, I thought that replacing the battery with a fully charged new one would do it, but no luck. Over Thanksgiving, I had a friend try and jump the car. Still no start, but we did hear the starter working- it was the saddest, puniest little sound I've ever hear from a car. We were definitely pulling power from my friend's VW- his lights would slightly dim every time I cranked- but no start.

Before shelling out the cash for a new starter, I wanted to ask the experts whether it could be something else, and how I could firgure that out. I peeked at the connections to the starter and they looked ok- would it be worth getting a voltmeter and the wiring diagram if the solenoid seems to be plunging properly? Could it be a different problem entirely, like a bad alternator that's binding up, or something else preventing the engine from turning over?

I just got a digital camera, so if you need any pictures, just let me know.