The AF will not cause it as it finds the same station but on a alternate/stronger frequency.
The rds will also not cause it, unless the one it is changing to all the time is broadcasting without realising it on the rds protocol, unlikley as there are big fines for this.
There is a bit inside that locks the stations, but whatever it is it can be fixed, by Fullers, these are who I use and they are the main Kenwood UK repair centre but do pretty much everything else as well.
They even find parts in stock for my old 1993 year Kenwood KRC 855 RL!!
tabetha