[amsat-bb] KR400 controller question

As both my KR400 controllers have blown bulbs I've modified them to use LEDs as per https://bit.ly/2TzeHud There is however a small difference that I'd like an opinion on as I'm not very electronically minded.

Eddie modified his KR-400RC however on my KR-400 controllers there is an additional 100R between the transformer and bulb. What is its purpose and should I leave it in or remove it when adding the diode, limiting resistor and LEDs shown in the mod?

CCT grabs showing the difference https://bit.ly/2FbKIo5

Paul Sussex Coast. JO00