I now have fixed my TV and wanted to come back with info on what I did. The sumptom was the TV would respond intermittently to IR commands from my Cable and harmony remotes but would work ok using the TV remote which was paired to the TV using Bluetooth (not IR).
There is a very small IR receiver board in the TV (approx 0.4" x 2.25") which is located in the lower right side corner of the TV (as you face the screen). You must open the TV to get to the board and this involves removing 8 long screws from the base, 4 long screws from the sides and 15 5/8" screws from the sides. There are also 6 machine screws with washers (input panel, mark their locations), 3 - 10mm self taping screws (input panel) and one hex nut (input panel).
After opening the set (removing the back panel) I found the IR board (see pictures). For the SV472XVT TV this part is mostly unavailable. I finally order a similar part (board number 3642-0042-0189) which would not fit the mounting space. If you have good soldering skills you can remove the IR sensor from this board and replace the sensor on the correct board (3642-0072-0189). It is best to cut the leads of the defective part and pull them out while heating with the soldering iron. Do not cut the leads of the new sensor but it must be removed from the replacement board. You will need to use solder wick to remove the solder from the holes.
After replacing the IR sensor, I installed the board and set the TV upright and tested it using my Harmony and Comcast remotes. It worked perfect.