Teslamade,
The red light (LED) is an indication there is a problem in that tube or that part of the cicuit. When I had my issue with the LED coming on it was because of a blown tube not only did I need to replace the tube I also needed to replace the fuse and rebias the amp. There is a fuse for each of the eight 6as7. Most likely you have multiple tubes that may be going bad and or a bias problem. The fuses protect the tubes from taking out the rest of the circuit. The bias has to do with voltage and tubes, there are adjustments inside the amp and this is be done with a few basic tools and volt meter. Some amps are easy to bias and some are more difficult, the Koras fall into the more difficult catagory as there are more steps involved. Be aware the voltages inside the amp are deadly and you may want to seek out a tech for this job. One note on the 6as7 tubes you want to use the Russian type 6as7 as it's been reported that other types of 6as7 tubes have a high failure rate in this amp.
