Need to replace cartridge in Monitor 1700
I have a significant loss of pressure in the shower and the temperature control is not working properly. I have cleaned out deposits in the shower head, and water pressure in the rest of the house is fine, so I conclude that the valve cartridge needs to be replaced. Delta's online information seems to indicate that this part should be covered by a lifetime warranty, but I do not have the purchase receipt as this was purchased in 2007 by the contractor who performed the bathroom update. How can I proceed?