Hi Dennis,
When you serviced the whistle/direction control, did you put any conductive grease where the contacts slide? I am rebuilding my ZW and I am up to taking that apart to clean and service the contacts. I saw one video where a guy put a dab of grease on all the contacts.
Also learned that a simple solution of lemon juice and table salt are a great cleaner for the metals parts. It has completely restore the arms for the rollers to shiny condition. Looks brand new!
Joe