Having a problem this year with tree sap dripping from leaves onto my outdoor track causing very sticky rails, which despite a lot of cleaning, soon spreads to loco & rolling stock wheels. Cutting down the trees not an option!
However.... have discovered wonderful Goo Gone (seems cheapest on eBay) - a small amount on a reasonable quality plastic scourer (type used for non stick pans) and its gone leaving a nice smell of oranges! Unfortunately back the next day, but what’s a bit of daily maintenance.... Hope this is useful, any other tips would be good to hear.