The Wurlitzer Kit 147 Remote Volume Control is used in monaural models
1900, 2000, 2100, 2104, 2150, 2200, 2204, 2250, 2300, 2304, 2310, 2400, 2404, 2410, 2500, 2504 and 2510.

Kit 147 is only used on monaural amplifiers type 530, 532, 536 and 540.

This listing is for the Remote Loudness Chassis Pan # 65390 seen in the photos.

THE CANCEL OR DOOR BELL BUTTON IS MISSING. 
This type of push button can still be bought at Home Depot for less than $5. 
Search their website for Newhouse Model # FMBSL-25

You are welcome to copy and save the Installation Instruction scans shown on this listing.