Dwell readings changing?

Initially I thought it might be my new timing light/dwell meter malfunctioning ( equus 5568 ), because the readings were so strange. It claims to be a "professional" timing light, so it's got to be good, right? ;) I'll either get a NOS distributor (if I can find one) or shell out the big bucks for an upgrade. Life's too short to mess around with questionable "remanufactured" junk from the chain stores. I've been down that road before.... I'll report back once I've done the transplant. Thanks again for all the advice.