Welcome to the wonderful world of 240D-ism!
Yup, the first time you change the oil is an education.
You've probably got the canister slightly cocked. Best way to replace the filter is NOT to use a ratchet to pull the housing into place. Fit the filter into the shell. use a dab of grease on the o-ring to hold it into place, use a socket and exstension to start the threads, rock the housing while you tighten the housing as much as you can by hand and THEN use the ratchet to snug it up. You should be able to spin the housing until it contacts the engine filter base housing.
After you've done it once or twice you'll get the hang of it. Just go slow and don't try to force it.