Rockwell PLC - backplace bad CRC error?

Does anyone know what could cause a bad CRC error on the chassis backplane of a Rockwell PLC? pic below
https://imgur.com/a/PSVrmVj

i cannot get to your site, but I have had this issue with the following on a slc 500 over the last 5+ years.

1. the chassis has water / trash in the backplane.
2. corrosion on the backplane.
3. corrosion on the I/o cards at the interface point, reseat several times to clean.
4. bad connection between racks on (2) 1746A10 RACKS.
5. bad connection of the plc to the rack
6. bad power supply connection.
8. bad power supply.

Yes, this is a very dirty / dusty plant and we have had seals to rot on ridged conduit hubs.

james

wow thanks a lot james. this is some excellent info. ive had these CRC errors before and after the backplane was swapped out. So i guess I'm looking for bad pins on the module cards or a bad power supply.

Thanks!