If you do want to have a go yourself, I found Martin Pyott's youtube videos helpful. I bought the Rowan belt upgrade kit (and the optional tool), and the worm gear ball bearings and have installed them without much hassle. See
https://www.youtube.com/watch?v=ol8B...el=MartinPyott He is a motor mechanic, so he is familiar with bearings and their adjustments.
Ed