I dropped the remote control for my E-Rod electrically operated drapes, and it stopped controlling the receiver/drape unit. I had another remote that still worked, so I knew the problem was with the remote, and not the drape motor unit. The IR transmitters were still flashing a signal, and on the oscilloscope the signal looked reasonable, but the carrier frequency was at 62.7 kHz.
I eventually traced the problem to the yellow square package, a crystal oscillator, and bought a 10-pack of them for $5 online (with a month wait time….). Replacing the oscillator restored the carrier frequency to 38 kHz and restored proper operation of the remote.