Yes, it is likely the sensor. Please PM me your mailing address and I will have a replacement sensor sent. Please ship me back the original once the replacement arrives.
As far as custom gauges, there is the issue of face dials as well as software. Depending on the software complexity (like a simple change in range) it may be feasible. The dials are usually a minimum order of 10 pcs, and it is at a premium price even at that level (we normally have them made in batches of 100's or 1000's). Basically, we could do just about anything for the right price, but I'm not sure that price would be right for you! I will do a little checking on what it would take to do your example gauge.