In article .com,
Patricia Quiggins m
wrote:

replying to Art Todesco, Patricia Quiggins wrote:
Just exactly where is the transmitter in the opener? We've been trying to
find dip switches. Where do you buy a transmitter?

I consider the remote control to be a "transmitter". Some openers may
not have a remote control, but are opened by a wired keypad.

Look for the Sears model number. It consists of two or three digits, a
decimal point, and several more digits. The first group of digits
indicates its actual manufacturer. You can find a cross-reference if
you search the web.

Take the Sears model number to the Sears Parts Direct website
http://www.searspartsdirect.com/. With any luck, there will be a
parts list that includes the keypad or dip switches you need.

If yours is not a Sears opener, that website may still have parts for it.

Fred