Thank you all. My Bee+ is also secondhand and I think more than 3 years old so that rules out the official route. It's making a strange (& annoying) noise I push it - the kind of noise you'd expect if you had a flat tire, almost like a paint roller sound - its coming from the back right wheel and when you lift the weight off that corner while still pushing it, the noise disappears. Not sure if that description makes any sense? Anyway, I'd be more than happy to replace a part myself but I don't know if its a problem with the wheel or the chassis, and I'd love to be able to get the problem diagnosed by someone with more expertise than myself before buying parts. Thanks for the Tommys recommendation, hopefully they can help.