Analog Instrument Cluster (Tachometer) not responding
 

The analog instrument cluster (tachometer) rpm needle does not move when ignition is turned on. I replaced the entire instrument dash harness (new) and also replaced the analog instrument cluster, I still have that problem. I notice if i thump the plexi-cover ( in front of the tachometer) it would engage at times.
I also notice when the instrument cluster is not fully placed in the dash ( before it is screwed into place) the rpm needle will respond. When it's placed properly (and screwed down) is when the needle does not respond (at times). I would appreciate if anyone can help me with this issue.