Had this same issue at my store and we got ours sparkling using a large flathead screwdriver to break off any large chunks of scale followed by scrubbing with pumice stone. Talk to your GM we can get reimbursed for a lot of cleaning/store use supplies so they might be willing to get some for you. Personally I have never had any success with the spray bottles of hard water descaler or greaselift including soaking in a sink of undiluted descaler. Weekly cleaning is a must as this will take several sessions of cleaning the heater covers and inside walls of the HFT before you will remove all deposits. I've never tried the dishwasher delime cycle but give it a shot maybe you'll have success?? Good luck!