These springs are suitable for Roland FJ-540 printers. These are the original Roland part (number 22175334). This spring goes under the DX4 Cap top.
 
Printer compatibility
Roland CJ-540
Roland FJ-540
Roland FLJ-300
Roland FP-740
Roland LEC-300
Roland LEC-300a
Roland LEC-330
Roland LEC-540
Roland LEF-12
Roland LEF-20
Roland LEJ-640
Roland RS-540
Roland RS-640
Roland SC-540
Roland SC-545ex
Roland SJ-1000
Roland SJ-1045ex
Roland SJ-540
Roland SJ-640
Roland SJ-645ex
Roland SJ-740
Roland SJ-745ex
Roland SP-300
Roland SP-300i
Roland SP-300v
Roland SP-540i
Roland SP-540v
Roland VP-300
Roland VP-300i
Roland VP-540
Roland VP-540i
Roland XC-540
Roland XC-540mt
Roland XJ-640
Roland XJ-740
Roland XJ-540