Mamiya RB67s are fantastic cameras but have been discontinued for well over 20 years. So it's important to know what to check when buying.
All medium format film and digital users will find this useful. Many of the checks and issues I discuss apply to Bronica, Hasselblad, Plaubel, Rollei, Pentax too.
I have 35+ years experience buying and selling Mamiya equipment ... I hope you find this helpful.
Jonathan Harris