Just bought several HP E3610/11s for work on ebay. All mid- 1990 vintage. Out of three, two (one of each kind) had both + and - binding posts color coded red. The third and newer 3611 has red, black, green as expected for +, -, GND.
Any ideas why would they do such a silly thing? These all came from different sellers and show no signs of damage or rework.
I love these units otherwise- very clean, easy to maintain and being HP all documentation is available.