Congrats! The 2Stroke really is a great little amp.
Those 100r resistors create an artificial center tap for the heater circuit to reduce hum. If your 2Stroke PT has a center tap (going to ground)for the 6.3v circuit, you don’t need the resistors. If you do not have a center tap for the 6.3v pair, you should add the resistors. They don’t have to connect to at the pilot light, but they need to go from each side of the 6.3v pair to ground. Again, if the 6.3v pair is center-tapped, you don’t need the resistors.
Here’s a link: http://www.freewebs.com/valvewizard/heater.html
Do not ground any extra center-taps on the PT that are not indicated in the 2Stroke layout.
Please let us know if this resolves the issue, if we don’t hear from you, we don’t know if our advice was helpful or not, and others don’t benefit from the topic. If the center-tap is not the issue, there are other things to check.