Probes don't often work between different brands (e.g. an EI probe won't work with a JPI instrument), but a lot of the older stuff (Alcor, Piper) might be more interchangable. It sounds like your system was toasted during the annual? Take a photo of the front of the gauge and post it here. There's so many people here that have a real depth of knowledge that someone might be able to identify it, and that might help determine if it's worthwhile spending any time or money to try to find new probes and salvage it by fixing the wiring, or if the cost of that is likely more expensive than just replacing it.
imo the EGT is the more important of the indicators. I never had CHT measurement in any of my Piper singles, just EGT, so if you have to replace you might save some money limiting to EGT only.