Having the same issue with my 68 912...I installed the WW flasher 211953227B as described in the thread and now when I pull the hazard switch, I hear a click near the pedals and nothing else. If the turn signals are activated pulling the hazard switch stops the turn signals. Paul mentioned above about "attached to neg earth" and I made sure the bracket holding the WW flasher has clean contact to bare metal and is installed similar to pic above. Any suggestions would be helpful!!
Thanks, Scott

Follow-up comments to my question below...After further research on how to bench test the hazard flasher relay, I found that the original hazard flasher actually worked and the replacement did not (returned). Original cause was the PO hazard wiring at the fuse block #4 was not on the battery side plus no hazard fuse...go figure! Fixed wiring, added fuse and reinstalled original hazard flasher relay and voila...GOT HAZARD LIGHTS:)!! Thank you all who post tips on these forums.

Thank you
 

I ended up with the same blue relay you got (found it on eBay - it was listed as an alternate to the part number originally listed above in this thread

"TURN SIGNAL RELAY / FLASHER UNIT
9 Pin 12 Volt
Has Color Coded Pins
Part #: 211953227B Condition: NEW
Alt Part #'s : 211953227B / 211953227BK
211953227BWW
VOLKSWAGEN
67-68 Type1
67-68 Type2
67-68 Type3
67-68 Ghia")

Your tip on grounding it worked like a charm. Thank you so much.

For others that end up with this same blue box, I recommend having a 2" machine screw and nut ready. I went with the #10-24 x 2" from Lowes and a wire with a ring terminal on each end, one on the bolt and the other to connect to the nearby ground for the yellow relay, then used double sided velcro to attach the box to the firewall.

Really appreciate all the contributors to this thread, finally have working hazards!

Coming out of storage this year, my 68 is having the same indicator/ hazards issue. Has anyone tried to rebuild the NLA flasher unit instead of replacing it? Otherwise, thanks for all the great info in this post, it’s a lifesaver.

Yes, I've tried but not managed to do it. I did it partially, but when I use the hazard switch thr lights just stay on, no flashing/blinking.