no carrier/carrier sense lost/RSSI out of range

One of our SMs has intermittent internet activity. Here are the symptoms/conclusions from troubleshooting:

1. RSSI Out of Range statistic increments (not very rapidly though) - any idea what this means?
2. I can ping the SM at all times directly through the ethernet port.
3. Some pings are lost to the AP. These pings coincide intermittently with the carrier sense lost statistic incrememnting or the radio re-registering on the AP.
4. The issue appears on multiple computers (including mine) so it’s not a network card issue.
5. rcv LT start HS and Rcv LT Result also have values in the stats
6. Customer is currently a 900 SM. They were a 2.4 but were recently changed.
7. There are no RF packet discards, only ethernet packet discards.

If there is a cabling issue, it exists on the wire between the radio and power injector. However, given that the SM loses registration with the AP, I am skeptical that this is only a cabling issue. The RSSI out of range seems to point to a RF mis-alignment according to other postings on the site.

Any suggestions?

Try another PSU, and swag a known good cable from the PSU to the radio for testing purposes. If there is a problem with the connector/cable you could be losing voltage to the SM