Asahi Pentax ESII acting up

I picked up a nice looking Asahi Pentax ESII but am having some trouble with it.

I put batteries in it and the meter is working just fine. But there are a couple of issues. One is that the mirror frequently refuses to come back down after releasing the shutter. I read in the manual that this is a built in function for certain situations, such as when you have the lens cap on, no lens attached etc. But mine does it more frequently than that. Sometimes it will come back down by turning the shutter speed dial out of auto mode and releasing again. But other times it won't come down for anything... Tonight it wouldn't come down until I took the batteries out and released the shutter one more time. Is this a malfunction or am I missing something real basic? I was testing it with an SMC 50/1.4 and the lens was set to "Auto". Batteries are new and battery test confirms they are good.

Secondly, even when it is working I am suspicious of the camera's automatic mode. The meter appears to work fine, but as I stop down the lens and release the shutter I don't hear anything that would suggest that the shutter speed is changing at all. It always sounds the same, like a very fast shutter speed, even with the lens stopped all the way down or in dark places, even when the meter is indicating a slow shutter speed.

Should I just assume this camera is broken? Or can anyone shed some light on the problem?

Hi,
The ESII is a great camera when it's working, but by today's standards the electronics are fairly crude and not as reliable as one might hope. That said, don't forget that the youngest of them are now 35 years old! You could have two problems. The mirror not returning may be a simple lubrication problem. This worked for me:
http://www.instructables.com/id/How-to-fix-a-ceased-mirror-on-a-Pentax-ES-Spotmati/#step1
However, that may be the least of your worries, as the shutter speed not changing with aperture setting sounds more like a problem with the electronics. Fortunately, such problems are rarely down to failure of a component and usually a matter of a dry joint - if it can be found. If the camera is in generally good shape, then I'd say it's well worth getting it fixed. Unlike many auto cameras, the fact that it was an automatic adaptation of a mechanical shutter mechanism means that even if the batteries and electronics should fail, you still have the option to use speeds from 1/60th to 1/1000th.
Best wishes,
Steve

check the mirror buffer foam, if its life is over it will be sticky and stop the mirror returning.

Thanks Steve and paulie. Steve, your link was most helpful. I actually opened it up, gave it a good blow and a couple drops of oil. It seems to work fine at faster shutter speeds, but as soon as I slow it down it still sticks frequently.
Paulie, the foam is very aged and broken down but not sticky at all; more like decayed and hard.

Anyway, there is a guy in texas who will give it a thorough CLA for less than $100 so I'm going to mail it off today!

Thanks for the responses.

It came back in the mail today working perfectly! Major kudos for Eric Hendrickson! Check him out at pentaxs.com