X10 control from the two HR12A remotes got much worse over the last few months and eventually failed completely, which meant I had to actually walk over to the lights and click the switches. Not to be tolerated, sez I, so I would walk to the bedroom and poke the appropriate buttons on the wired controller (long since obsolete) by the bed. That worked perfectly, which eventually convinced me to dismantle the TM 751 transceiver.
It’s not good when soot plates the case:
I like how they capacitively coupled RF from the antenna for complete line-voltage isolation.
The PCB looked like it got rather hot over there on the left side:
A Zener diode on the component side of the PCB looked a bit toasty, so I decided this gadget had passed its best-used-by-date and dropped it in the electronics recycling box (after harvesting the antenna, just in case).
A new-in-box TM 751 from eBay arrived a few days ago and works just fine.
Done!
The Smell of Molten Projects in the Morning 
I was lucky enough to score a bunch of surplus NOS Leviton X10 RF controllers for a very few dollars each. The official X10 ones seem quite badly made: I had the case separate on one on unplugging it, leaving hot contacts open to fingers.
Apparently the late Tom “Soul of a New Machine” West’s extensive X10 setup caused his daughter some years of mystery lights-going-on-and-off in the house after he passed away.
Having started doing X10 back when it was the New New Thing, the caps in those old brown modules aged out long ago. They were built like tanks; the “new” white ones suffer from cheapnification.
The smart kids have moved on to Zigbee / BTLE / WiFi-based gadgetry, with stunningly high per-device prices that leave me cold and seemingly unavoidable network security exposures. I don’t see any reason to deliberately install Internet-accessible gateways behind my firewall, just to flip a switch from across the room.