From what you described, it sounds like the timer motor is OK, but the mechanism that it drives has some kind of dead spot or is otherwise getting hung up.  This seems odd for a barely used machine.  I wouldn't know exactly how to analyze this, and finding a replacement mechanism could be a challenge since yours isn't a model that was sold to the general public. 

The timer assembly is easy to access if you want to investigate what might be wrong.  The control panel is held by a few screws.  Remove those and it will open up to reveal the wiring, etc.

There are experts here who may be able to provide a diagnosis or troubleshooting advice.  You may need to be patient and allow them some time to reply.

I'm unfamiliar with this model but I would first confirm there's no thermostatic hold which stalls the timer until a target temperature it met.

What is the model # of your DW, its on a sticker on the left side of the tank, visible with the door open, it starts with the letter K

We can confirm if the timer is supposed stall in the main wash.

John 

I figured that since it's a 23 series, it would behave like the 21 and 22 which did not pause for heating like earlier models, so I ruled out water heating as the reason for the stall.

I don't think there is any thermal hold on this DW, you can try pushing Energy Saver Wash to by pass any water heating if you want to try this.

Does the timer feel stiff and kind of stick where it gets stuck ?, If so open up the control panel and spray some silicone spray lubricant in the timer on the cam etc [ Do Not Use WD 40 ] this often helps if the timer gets stuck.

John L.

Good catch, Glen. It appears a thermal hold began with the 23 series machines.

I don't see where the verbiage in the manual cites a specified heating period where all action stops.  Instead, it reads that the cycle will continue to wash while the water is being heated. 

As a former owner of a KDI21, this matches my experience.  I don't think there is any difference between the automatic water heating across the 21, 22 and 23 series.  Taking this further, I think the term "Automatic Water Heating" means that the heating occurs while machine is running instead of a silent period of inactivity while the water is heated, which was true for the 20 and earlier series with the feature that added heat to the tap-hot water.

I don't see where the verbiage in the manual cites a specified heating period where all action stops.

All action never stops, just the timer motor. It's stated under "Time Needed To Heat Water" how lower water temperatures will extend time during the wash portion of the cycle until 140F is met. The only way it could achieve a longer cycle is by stalling the timer.

heating occurs while machine is running instead of a silent period of inactivity...

That matches up with what the poster states. The timer stalls during the wash cycle until 140F is reached, then continues advancing. I don't think the poster ran the machine long enough to achieve 140F during the wash portion of the cycle for the timer to advance.

I never used these newer machines before so I may be overlooking something here. It doesn't rule out a bad timer/dead spot if it never advances once 140F is achieved during the wash portion of the cycle.

Dan, thanks for clarifying.  That makes sense. 

Considering that the subject machine has barely been used, I think the timer's stall-out for heating is likely what's causing the OP to think there's a dead spot.

Great news!  After sitting unused for so many years, I guess your machine just needed some time to become fully functional again.  I can relate to that most mornings, particularly before coffee.

Remove the leads to the bi metals and carefully inspect them. The seals on the dispenser cups and doors can leak, causing corrosion on the terminals of the wires and/or the bi-metal connections.