I just purchased this LGB Christmas Trolley set on Ebay

When I opened it up to lube it I discovered this…

I got it all cleaned out and lubed and it runs great! Which now brings me to my issue. The interior lights don’t work. This is one of the older trolley’s with the older style lighting and connector plugs between the cars. I tried powering just the lights and nothing. I guess it’s possible that ALL 4 lights are blown (2 in each car) even though they don’t look to be so.