running timing mark

[rogranger]

just put a distributor in my 1986 2.9 ranger. Went to set the timing, and the timing mark is moving all the way around the pulley. The balancer doesn't seem loose when I grab it and shake, but I haven;t loosend all the belts yet. Spout is disconnected. The mark moves and can be seen on all sides of pulley with timing light( fairly new otc electronic ). What could cause this other than a broken and slipping harmonic balancer?
Thanks for any help

 

[holyford86]

what wire are you clipping the timing light to? should be passenger side front cylinder for #1