Thanks to all who responded. I had an old, but barely used, honeywell S400 timer on hand and a local EFM dealer installed a new ARGO 822II relay in conjunction with that timer. Normally I do all my work myself, and if I had used an exact replacement I certainly would have been comfortable doing that. Actually I did find a rebuilt Honeywell R183B for $300, but the fix I did was about half that.
Everything is working well. I will plan on installing a low water cutoff next spring. In addition, on recommendation of the service person, I cleaned the pigtail etc. to which the pressuretrol/pressure guage is attached, something I had never done. Might save a bit of coal if the system was pressurized but the t-stat was still calling for heat. Also set the pressure to 1 1/2 lb cut outwith a 1/2 lb differential from 2 lb cutout and 1 lb differential.
Thanks again, Jim