The LPSL is the 5v regulator LP2985-50 that allows the circuit to work at a better voltage range then the PERS (Another version of the receiver switch that the manufacturer offers) 2-6v range.
The MN9 X1 is a N Channel Mosfet similar to Diodes Inc DMN2041L-7.
The X1 is a Year/Month Code.
The 00J1 is most likely a Microchip PIC10F200 microcontroller, based on the number code 00J1 (00 is product, as in F200, J1 is a tracing code, like lot/bin/manufacturing number). 256 word code size, 16bytes ram, 4 I/O (1 input only) with 1 8-bit timer. The voltage range of 2~6v of the NERS is close to the 2~5.5v of the PIC10F200. Also, the pinout as you have shown, is very much the same, with pin 2 being ground and pin 5 being V+.
The code emulates a servo control circuit. It monitors pin 1 for a pulse between 1ms and 2ms every 20ms (50hz), then toggles pin 3 based on what it receives (Anything longer than 1.54ms switches it to On, anything less than 1.46ms switches it to Off). Pin 4 and pin 2 can be used for features, like the reverse output, and safety operation.
That's all it does. You could do the same with any microcontroller. This site has three versions using the same basic idea (Pic10f2xx reading signals, mosfet or direct gpio out)
This is a similar project, using a pic12f, with schematic and code.