Jim,
If you have the 9200 series, it is likely the Progressive Dynamics (PDI) 9200 series.
Here's a link to PDI's website.
It's likely the 9260C. The PDI unit does not mount in the wall. I believe the WFCO brand does.
The PDI unit is likely mounted behind the bulkhead wall near the steps.
The warranty from PDI is 2 years. I would give them a call before sourcing a replacement on your own.
Their number is: 269-781-4241