I dropped an intake manifold (thick) washer into oil channel near number 7 cylinder. I tried using a magnet but not luck. What should I do at this point? I was thinking of dropping the oil pan? Any advice would be gratefully appreciated. Thank you

 

have you tried using vacuum to suck it out or let down a magnet in a string?

 

I would not worry too much about it if you think it made it all the way down into the bottom of the oil pan
It is liable to stay right there
You could stick a strong magnet on the bottom of the oil pan and run it for years IMO
Have you tried a good 40 dollar Snap-on flexible magnet down the hole?
I'd start there, with two expensive magnets
Mine only releases the magnet when you push the button
That allows you to fish around without getting your magnet stuck to everything

 

You are looking for a Snap-On flexible magnet with a spring loaded push button
About the diameter of a pencil and about 18 inches long

 

bore scope would show if its stick in oil passage.

If it made it to oil pan, use flex magnet through drain plug hole to fish it out

IMHO, I would not proceed until it is removed from engine.