I recently switched to an Imco lower unit and now my speedometer doesn't work. Worked fine with the Bravo lower so I am thinking it must be in the lower or the plastic fitting that holds the hose into the lower may have a problem. I don't see any separate hole in the front of the drive , like on the Bravo's. It must get the water for the speedo from the water pick up slot at the front of the drive. Any suggestions on an easy way to troubleshoot this problem?

Take hose off of speedo head under the dash, blow compressed air through it.

Or get a gps speedo.