Okay so I assume a few of you who bought a Steam Along Thomas may not have o-rings in your reservoir area, or it may have been lost or broken
Having an o-ring here is very beneficial from water leaking on the tracks and makes your steam along last longer before refilling at the water tower. It's also, by design, meant to have one in case you didn't know if you bought them used.
Anyway here's a link to buy the exact replacement of them:
https://www.amazon.com/gp/aw/d/B00N3V7HC...asin_title
Having an o-ring here is very beneficial from water leaking on the tracks and makes your steam along last longer before refilling at the water tower. It's also, by design, meant to have one in case you didn't know if you bought them used.
Anyway here's a link to buy the exact replacement of them:
https://www.amazon.com/gp/aw/d/B00N3V7HC...asin_title