1988 Toyota Camry Lifter washers?

Engine Mechanical problem
1988 Toyota Camry Two Wheel Drive Automatic

I have an 88 Camry that has nevr given me a problem. A few days ago it started knocking and from a lot of research done on-line it sounds like it's a nylon washer (or washers) for the rocker arms.

How do I explain this to a mechanic without getting the typical, ordinary, 99.9% of the time CROOKED answer that it's, "A blown flange gonkulator" and the cost is $2200?

One of the posts I found summed it up pretty perfectly:

"There should be small white nylon washers that keep the rockers from rubbing - a lot of the time, these washers will break down and "dissolve" and no one will ever know they were there. If you go to the toyota dealer parts dept, they can pull a blown up view of the head and get the part number for those washers. Install them as shown in the blown up diagram, or your chiltons/ haynes manual, and the noise will be gone!"

Any tips will be appreciated. I hate to sound like a stereotypical consumer but I have ALWAYS been mislead by mechanics. ALWAYS. One time I got a $600 quote and the job turned out to be $28 in parts and 4 hours work (from a friend and I on a sidewalk with no lift so THAT'S where the time went.)

Thanks for the answers!