Rob you have French threaded bottom bracket cups .. if you look on the end they have 35 x 1 stamped in them which means although the shell width is 68mm the threads per inch are all wrong 25.4 French 24 English / Italian and also both cups are right hand threaded as per Italian. I am going to suggest you need an English bottom bracket (don't sue me if I'm wrong!) based on the fact one side would screw in a few turns before the threads jamed and the other side wouldn't start - it should have started and screwed in the same amount of turns if it was an Italian threaded shell in your frame. Even though it's a Cenelli lug the frame is english by Dave Marsh ..
Rob you have French threaded bottom bracket cups .. if you look on the end they have 35 x 1 stamped in them which means although the shell width is 68mm the threads per inch are all wrong 25.4 French 24 English / Italian and also both cups are right hand threaded as per Italian. I am going to suggest you need an English bottom bracket (don't sue me if I'm wrong!) based on the fact one side would screw in a few turns before the threads jamed and the other side wouldn't start - it should have started and screwed in the same amount of turns if it was an Italian threaded shell in your frame. Even though it's a Cenelli lug the frame is english by Dave Marsh ..