Take a look at this large picture: RS timer plate
Note the two springs - the long one is hooked to the anti backlash pawl and the short one is hooked to the index lever.
Both the pawl and index lever wear out over time and need to be replaced.
When they go bad the unit sticks in any given cycle and runs and runs...
Notice the tip of the index lever that fits into the notch. When this tips is worn off by the wheel your problems begin.
Now the bad news: Your entire valve and electronic controls are obsolete and no longer supported by RS.
RS dealers are instructed to replace the entire valve with a composite silver or gold series valve (bastardized Fleck valves).
The index lever has been out of production for over a year and is very rare.
this is your problem you can try to locate a new index lever and abp, then get someone to rebuild your timer plate -
OR, you can upgrade to a new valve. I suggest and install Fleck 2510SE valves.