Check your fuses. They are on two different circuits.

They are controlled by the chase board under the playfield. Orange wires go to this and the bowl. You can disconnect the molex and switch them to see if the other string lights. You don't have to remove the ramp to check, just switch the 2 connections. The larger more square style ones, not the longer ones on the board itself or the connections to the lights themselves. Just follow the wires and you will see what I mean. If it lights after doing that, then it's something on the board most likely. If not the could be a bad connection to the string that doesn't light, or a cold solder or bad trace on the string. Did they work before? It may even just be disconnected if someone worked on it in the past. Hopefully it's not your chase board since repairing that is difficult since it tends to disintgrate if you try to work on it due to heat damage and age. If it's bad Bill Ung makes a replacement board for around 100. Just search and you can easily find his site and contact info. He is pretty good at helping diagnose even if you don't happen to buy a board. Good guy.

If it is your board I have two spare ones that I would be willing to let go. Both work one is brand new and I am sure we could make a deal.