I'm having the exact same issue with pulsating lights but mine only seems to do it at speed and it only does it with the light bar turned on. So far I have cleaned the battery contacts, rectifier connector, and checked some of the wiring. I found that I had a badly corroded wire on one of the terminals where the stator plugs in to the wiring harness so I cut the wires and re-terminated them. Had to remove the connector housing and label the wires to connect them back up properly but I'm going to try it out tomorrow and see how she runs. I haven't changed the battery yet and thought that might be the culprit (almost 3 years old) since I had to bump start it a while ago but the battery showed a good voltage after putting it on my trickle charger (only took about 20-30 minutes top off the charge).
I also used a multimeter to check the rectifier (as per one of the above posts - thanks!) and it checked out fine. If the battery is still good and she starts then I'll check the voltages across the stator. Tried to take the rectifier out but the connector was too big to fit through the space the wire goes through. Looks like I would have to remove the engine from the frame in order to pull the rectifier without cutting the wire to the connector.
