I second what Guy has said...
If your 2030 is an early version it was equipped with an MS2 transmission
or because it is a Bavaria
, perhaps it has a 120S saildrive
. Both of these used a cone clutch
shift mechanism where the cone was moved up and down by a shift shoe which rode
in an eccentric groove. Part of the assembly procedure of the transmission was to shim this shift shoe so that there was a high drag spot as the shoe ran past the eccentric. Normally this drag wasn't enough that you could feel it with a wrench on the crankshaft, but if something is amiss in the drive, perhaps the drag has increased. You can eliminate this as a possibility by loosening the two bolts on the shift mechanism on the side of the gear
case and sliding the shifter out.
If this doesn't help, or you have a different transmission, then it's back to the ideas already mentioned.