You should be able to get the p/n off the old relay. Never seen a Klixon that didn't have it marked.
I have the same promble what iis the number and what kind is it name brand?UPDATE:
Found a universal electronic start relay, wired it in and we're in business. Pretty straightforward install which required crimping a couple new connectors on and getting a little creative inside the control box to fit it all back inside. Best part was the new relay was only $18 whereas the now D/C'd OEM part was $35 and unobtanium. Don't toss those old power tools, fix 'em!