ER 01-clean contacts and overexposure on 35f2

The Canon 35f2 has been my most used lens. For a couple of weeks, I have been getting the error message to clean the contacts on my 60D. I did this with lens fluid, and the problem persisted - it was intermittent. If you turn the camera off and on, the error signal went away. However, it reappears after perhaps 5-10 shots. I tried using some alcohol. The camera and lens were fine for a few shots, and the error message returned.
I thought that this was the camera, but I tried different lenses, with no more errors. This tells me that there is a problem with the lens. Most shots are overexposed, with an occasional one a few stops over.
I fear that I have sticky aperture blades.
Is this likely? Anyone have any idea what a fix would cost? Is it something else?
I have used the lens for perhaps 2 1/2 years and I baby my photo gear.
I welcome suggestions, and will call Canon service in the morning.

Hey Arty,

I've googled that error - there is a lot of nonsense responses. one of my lens does the same.
Probably the most logical solution in the responses is the aperture flex cable or aperture mechanism (lack for a better word) could be the cause.
Your on the right path with Canon, keep us posted on the result.

Cheers
Michael

sticky blades should be easy to check for, bung camera on Av and set to something like F/16 or so. Hit the depth-of-field preview button while looking thru the viewfinder and see if it goes darker & lighter with each button press (and/or comes up with said error)

From the overexposed issue, I'd say it could well be sticky blades. Give the depth-of-field button a workout to f/22 and back a few times and see if it changes any.

part number for said diaphram is cg2-0351-000 but couldn't find any prices for this during a quick search so not sure what would cost to fix (I don't think they'd do much other than replace the diaphram these days)

I set the camera on av and set the aperture to 22, as suggested. I got varying results, upon using the depth of field preview, including dark and light screens. I didn't get the er01 signal, but something is wrong with the lens. I called Canon today and sent the lens in for a quote...what a bummer. a friend with A Nikon has told me they get a 5 year warranty with their lenses.
Canon should do better.