KZ900 Slow flashers

Hi, my KZ900 flashers blink very slowly   I cleaned the connectors but it's the same. 

Any suggestions !

Thank you in advance

What bulbs are you using? Have you checked your grounds with a voltmeter, little current like when a bulb is out causes fast flashing, too much causes slow (contact bends further)

It's a 12 V 23 W. I will check ground tomorrow.

Thanks Wookie !