The beep is focus confirmation from the camera I think.

My MZ3 will do that if I switch on the sound. If I set it to autofocus and use a manual lens it will not release the shutter unless the image is in focus - perhaps that's something else you could try?

Have you formatted the microdrive in the camera?

The MX and ME were released at the same time and are both compatible with your lenses, but both cameras are entirely different.

The MX, as you know, is fully manual and you set everything yourself.

The ME is fully automatic. You set the aperture on the lens and it sets the shutter speed. There is only a 100X setting for flash use, and there are no manual speeds.

If you want this camera with manual speeds, you need the ME Super, which has manual settings via push buttons rather than a dial.

Within its limirtations, the ME is a very nice body, but all these older Pentax auto shutter cameras do have a tendency to fail in the electronics, so you need a supernb example if you want to buy one.

I have owned and used probably 6 or 7 of the ME, ME Super, MEF, MV, MG series and all have eventually died the same way.

But when I find a nice one at the right price, I will definitely buy another. The smoothness of that wind on lever has to be experienced to be believed....

The meter is turned on with a half pressure on the shutter release - is the shutter lock partly turned and stopping the button resting in its normal position?

Otherwise, could be a faulty switch on the shutter button or on the wind lever, which enables you to have the meter permanently on when pulled out slightly, and a quote for repair looks likely to be needed.

Of the lenses you list I have tried the 24mm, 28mm, 50mm, 105mm and all of them have been excellent.

Maybe the 28mm and 105mm stand out as particularly fine, but also the 150mm, which you don't mention, is reckoned to be a superb performer.

I don't think you can go far wrong with Super Takumar and later lenses!

There is just one 100-300mm lens, which is in the current autofocus range. I presume it will be a SMC FA.

In general, you get what you pay for, and no 28-300mm zoom is going to equal the performance of a more modestly specified lens anyway.

I have read that the Pentax 100-300mm is quite a good performer, though, and I believe that it is reasonably priced. The Pentax 80-320mm could also be on your list.

If you buy Pentax you have access to several decades of interesting, useful and high quality lenses.

If you buy Nikon or Fuji you have access in almost the same way to all the Nikon lenses, which are also of highest quality.

If you buy Canon, they have changed the lens mount several times and the choice is more restricted, and although they do make some fine cameras and lenses I have never liked the design details. I also think cameras such as the 300D are rather more "platicky" than some others.

I would be happiest with an *istD or the Nikon 70D or the Fuji S2 or S3 Pro. The Pentax *istDS is unseen so far, but could be the camera that makes me plunge for a digital SLR.

So far I have been upgrading digital SLR-style cameras, relatively low cost and pretty good for the purposes I have wanted them for.

As I understand it, the *istD delivers pictures straight from the camera which will appear softer than some and of lower saturation, but this is a good thing because they are not over-processed in camera and sharpen up very nicely in Photoshop. The finished pictures should be the equal of anything else.

You can go for Pentax and still use your existing lenses with a degree of conmpatibility which is very impressive.

However, if I was looking at alternatives I would be looking at Nikon and Fuji, not Canon.

It is not recommended to use lithium cells in the MX and similar cameras, they are not designed for them. It may well be that the nominal voltage is actually higher, but I think it is because of the heat generation from the lithium cell.

It is better IMHO to stick with the instructions and use silver oxide or alkaline G13 cells.