Recently I had some severe engine problems and had to tow my 82 240d home. The issue was a loud noise (thackthackthack) and a loss of power. When I took it home, for safe measure I replaced vacuum lines. The engine sat in idle fine but when I tried to pull it out it started making the engine noise after a minute of driving low rpm, so I cut the engine and pushed it home. Now it won't start again (although the starter works and has been replaced recently).

Tonight I opened the valve cover and attempted to check to seek if the tdc notches lined up, make sure the timing belt wasn't out of place, and check to cam for cracks. There are no superficial signs of stress, however I could not check the notches or the timing because I'm not able to turn the engine from the power steering pump bolt (the belt slips without turning anything but is not obviously loose). I think I may have an engine lock up. Anyone advice from you experts would be immensely appreciated in my time of Benz crisis.

Specs: 1982 Benz 240d with an auto tranny.