Yeah, I just used these from Tayda, Red Diffused, 3mm, Forward voltage@IF=20mA: 2.0-2.2V, Luminous intensity(MCD): 4,000 - 6,000 - https://www.taydaelectronics.com/leds/round-leds/3mm-leds/led-3mm-red.html
I'd like to see the schematic and compare it to the original TS-9 and see what exactly...