We put on new hoses a year and a half ago when we moved, so they should be still good. However, for future reference, how often should the hoses be checked? We use rainwater in the washer heated by an on-demand water heater.
Since I checked the filter and ran one pack of Tide Washing Machine Cleaner, I have done one load of whites. I used Tide HE to spot clean the black spots and washed the load with Tide HE and OxiClean. The load came out with no spots. I am not going to take myself out of this email string though, until I spot clean and wash the badly spotted white sheets. I will report back then.
FYI to all who have helped, the manual that came with the machine provided no suggestions except related to the detergent. I appreciate all the help.