I had a similar leak on my Type III.  Check the windshield wipers 
where they go thorugh the body.  Water will find it's way though if 
there is an opening.  I tried lots of proper ways to stop the leak, 
but finally poked a hole in a plastic film canister lid, took the 
wiper off the shaft & fit the lid over the shaft.  No more leaks.

Jeff '80 Westi (still have the '67 Sqbk lawnornament! and it still 
doesn't leak!)