Hi. Just wanted to say "thank you" to the contributors. (and thank you, posthumously, Jinman)... as a "novice" (we're all a "novice" at something, right?) I was trying to understand difference between the "relay" and the "timer" (whenever I searched "NH TC40 glow plug relay" -- it went to the "timer"). So, I finally figured out the "relay" is a commonly utilized item that I was able to pull and take to the auto parts store ($9) ... and it did the job. (glow plug indicator now comes on, on the dash; goes off in 10 seconds or so and tractor starts more easily when cold). I had also ordered the "kubota timer" as above, for $25, and will have it as a spare part going forward.
BIG THANK YOU (all) for the help...