LOL, good one!
I like this idea, I’ve long thought it might be fun to hunt for it myself, but there are too many variables I don’t have good data for (expected spacecraft orientation, albedo for solar radiation pressure, etc).
It seems that it’s last known orbit would be a good start. Then use computer generated orbits to calculate the nearest possible match after 40 years. You should be able to narrow it down to a sector of sky that is the most likely, then begin scanning..............