http://www.exhaustgas.com/
I know that they are still carring probes and such for the Racepak,
you may just want to give them a call and ask.
I ordered weld on probe mounts last month from them.
I talked to them 2 weeks ago and they still carry parts for them. They have just stopped making the gauges. I would call the 800 number and ask about service.
Food for thought. The last time I ordered batteries from EGT they said that they still have parts to repair racepac gauges but they also said that one of the leading causes of failures they see with them is the batteries leaking and corroding the circuit board. They recommended leaving the batteries out if I really didn't need them.