I Just Baught A Brother Printer It;s A Mfc440nc With The Lc51 Cartridge I Am Not Fimiler With Thes Cartridges And Refilling Them When I Installed Them I Din Not Notice A Window On The Front Of Them In The Set Up It Said Not To Remove Them Except To Replace Them It Would Mess Up The Ink Level Is This True ? Also The Member Drmike Said He Install A Continuous Feed For His Cartridges I Seen Thes For Different Brands But Not For Brother Where Can You Get These Ken