New guy turn signal??

[Kurtkx250f]

Hello, I am new to joining this forum. I have been watching from the sidelines and finally decided to jump in. I am currently having problems with the turn signals on my 1979 GS1000L. I have read several of the post regarding turn signals, but did not find one that covered my specific situation. The turn signals seem to work perfect when the bike is parked and running as well as when at a steady pace. It is when down shifting or decelerating that the turn signals shut off. I have to continually cancel and press the turn signal on for 15-20 seconds before the will turn on again. I know that they have a automatic cancel on them, but this does not seem right. The only things that I have changed on the bike is the flasher (prongs broke), so I put an automotive electronic flasher on. Also, the battery it is running on is out of my Kawasaki prairie 300. could the battery be the culprit. Any ideas would be appreciated.

[7981GS]

Check/clean all of the grounding rings and the plugs?
It could be the flasher but... ???

Eric