How often do you clean your contacts?

I use a dry cloth.

Dry lint free cloth.

Good point, well presented, but surely the mating surfaces of the mount, I mean the bayonet part, determine the proximity of the lens & camera surfaces and the seal just squishes a bit.

Never (knowingly) but if I had to.

IPA sprayed onto a cloth first or electrical contact cleaner spray likewise. Probably a Pec Pad as I bought 100 ages ago.

Never had a problem though. (till now!)

Also the 2nd hand Z-1 and the ebay lenses I've used on that have all worked after just a general wipe with an IPA cloth.

Occasionally, buy never with WD-40 Having been a bit of a 'Hi-Fi' nerd in my time, and made many a custom interconnect, I have always found pure (if you can get it) isopropanol/propan-2-ol to be effective and safe as long as you don't mix it with tonic and swallow

Reputedly better, but more expensive, are DeoxIT D5 or, if you really want to go to town, DeoxIT Gold GN5. Both are safe on plastics and leave no residue.

More info and prices here:link and link

I have heard that Windolene does a good job, too

Iso Propyl Alcohol (Iso Propanol) as stated above is safe on audio styli, but beware that it degrades plastics by removing the plasticiser.

So a clean dry cloth is best, very slightly dampened if necessary. The contacts should not be so dirty that anything more is needed.

I answered "never" also, sounds to me like the camera wouldn't fire because the flash hadn't charged:.
As for the weather sealing, surely the "rubber" seal is made from something that has minimum friction properties so no luberication would be necessary.

My guess for the weather seal is some silicon compound.

I shan't worry about using IPA, it's once in a blue moon and I'm sure it has no more deleterious effect than the sweat in my palms, the UV from the sun or the minerals deposited from water in the damp cloth.

IPA will de-grease where water won't and it will also take off water soluble stuff too, IIRC.

That occured to me too, but when I checked at the time, it was charged and ready to fire.

This could become the Pentax user greeting, a firm handshake, with your hand covered with a damp lint free cloth?

At least you'd know who you just sat next to at the cinema!

I use the tail of my t-shirt... Nothing else. K.

You have posh T-shirts if they have tails .

I have never cleaned contacts. It would never occur to me to clean them tbh .

Before or after it's been washed?

I put 'never', so far I haven't needed to clean the contacts because there's always a lens on the body.

It seems to work for me.

Many years ago a helpful person sorted out the telephone exchange with WD40 on a ship I knew. Never did work after that. Contact cleaning on my bodies and lenses is done in the Womble fashion for me too, tee, polo or whatever.

ummmn..
logic fail....
by your own description, the telephone exchange was already not working.... so the application of wd-40 failed to fix it..permanently.... and it did not work before or after that...

by way of comparison, I could say the fuel pump in my car failed, I sprayed wd-40 on it, and it never again worked after that... doesn't mean wd-40 wrecked the fuel pump in my car.

so...
that statement does not work as an indictment against wd-40.....
just sayin'
that is all.