K-Line K-120 Rewire for Green aspect default instead of Red aspect

The replacement parts list suggests separate red and green screw-in bulbs.  Hence, wouldn't you just swap bulbs?  Unless it's a red-over-green vs. green-over-red issue?

Thanks for the response. The wiring on this unit is in series for each signal head. Changing bulbs doesn't get desired effect as the scheme apparently has to do with different voltages required by the red and green bulbs.

I've tried all variations of wiring with no sucess as changing default aspect to GREEN without RED also on. A post by dTrainmaster from 2018 explains the circuit function. Once Lionel assumed production of this product the aspect display issue was corrected. I can get the operational manual but am unable to get a wire schematic for the new product.

Right, Dtrainmaster earned a gold star analyzing the circuit. Here's his award winning post! 

As you purchased it used, was it sight unseen or did you see it work?

What is it doing (presumably on all 4 units)?  Apparently you're getting RED & GREEN when untriggered (default)?  What do you get when triggered?  How does brightness of each bulb change between default and triggered?  What voltage are you using?

The bulb color does not affect how the circuit works.  Call it the upper bulb and lower bulb.  You should be able to swap red and green bulbs, or use two green bulbs, or two red bulbs, and the circuit should (mis)behave in the same way relative to the upper and lower bulbs.  Does it?

Thank s for your response and time. It does work as designated in included document. Red bulb is on by default when no train is within isolated rail block but green bulb  is also dimly lit. When the wheels enter isolated block, red light goes out completely and green light glows brightly. I tried swapping bulbs and behavior is the same respectively. However red bulb glows a wee tad brighter at default when swapped out and isolated block is unoccupied. It seems that the red bulb requires slightly less voltage than the green to glow. I am using the prescribed 10-12 AC track voltage.

So what I'm hearing is it basically works.  Swap the red and green bulbs.  In which case in default you'll have Green ON with a dim Red.  And when occupied you will have solid Red (no Green).

In Dtrainmaster's analysis, in the default condition the OFF bulb is actually powered...in his example the OFF bulb receives 1/6th the power of the ON bulb.  In other words, this is the expected behavior.  You might try adjusting the 10-12 AC track voltage upwards to see if this increases the contrast between the ON bulb and the DIM bulb.

Separately, it's somewhat curious that your red and green bulbs were swapped in the first place...as if the previous user might have fiddled with the wiring or perhaps installed a different voltage or type of red and green bulb.

Thanks for the follow up.  I've accepted that it will function okay by swapping bulbs. Additionally I replaced the green bulb with a 1447 solid green 18volt bulb from Town & Country. The solid green bulb helps diminish the fact that the red lights when no train is in the insulated rail block. You've been great. Thanks again for your time and wisdom.