Thank you your response.
BOTH of my mfj-452 w/KB, are brand new & NEVER did work OUTPUT CORRECTLY, since day one!!!!!.
Looked on MFJ URL; site has NO model of mfj-493 keyer. Closes they have are: 39265C, 4936C24 & ...others .
I'm elderly, also and handicap
I think the latest is the MFJ-492 (the 492X has more memory). MFJ has produced versions of this keyer since the 1990s. The one I have is no longer in the list.
The 452 you have gets decent reviews. Have you tried a different keyboard? The manual for the 452 says that if you don't use an AT style keyboard you could damage the keyer and they specifically mention an XT keyboard being a problem.
Here is what an XT style keyboard looks like: http://www.pcguide.com/ref/kb/layout/stdXT83-c.html
Make sure you're using the right keyboard before you contact MFJ.
Have you contacted MFJ? They do have a repair service. Technical help is at 601-323-0549
Good luck. Using a kb for CW is no big deal if you're handicapped. I'm 73 and have arthritic hands but still can do a bug and a paddle but I can sure see how it would be a problem for some.