Before Washwood Heath Depot became just for buses, it was of course for trams.
When I was about aged 12, some boy at school told me that If I wrote to the the depot manager I could get a permit to visit.
So I wrote, and received the permit, and on the appointed visit day was taken around the depot, no parents in tow.
I was taken down into the inspection pit under a tram, and although I didn`t understand much of what I saw, generally felt it had been worth doing.