Speed sensors

GrampsVanTruk is doing rather poorly, I'm afraid. He is a 1990 Honda Accord (automatic transmission), but he's been going strong until a few weeks ago. The speedometer doesn't read any useful information - meaning it's completely not registering any speed. Online research tells us that the speed sensors need to be cleaned, but NOT the VSS (vehicle speed sensor). Rather, the NM (mainshaft) and NC (countershaft) speed sensors need to be cleaned. Last night we spend a few hours trying to find where these darn things are. We ended up taking out the air filter system and the battery to get at the innards of the car, but couldn't find anything that vaguely resembles the NM and NC speed sensors. The next plan of attack is to raise the car on two jacks, get under there, and take a look around.