Ron, I'm pretty sure I know what's wrong with your shutter. First let me go through the list, starting with your question.

There should be an indent at every speed. You are right, don't force it!

It's not a variable speed shutter, in that it is not made to run at speeds other than those indexed by speed numbers. IE, there is no proper speed between 1/25 and 1/50, etc.

Your's is an original Mat, made from 1957 to somewhere around 1971. They made a gob of them.

The thing mentioned about what not to do is, Never try to use the self timer when the flash sync is set to "M". There is a lockout to prevent it, built into the shutter, but I've fixed enough of them to know that people can overcome any idiot proofing that Copal built into the shutter on these cameras.

From having many of these shutters apart, I'd say that yours has a bent indexing pin on the speed gearset pallet wheel. The shutter speeds are set by a rotating cam on the front of the shutter. This cam has a number of slots cut in it to position a number of pins in the shutter works that give you the "B" setting, slow, medium and fast speeds. This little pin I'm talking about pushes the pallet wheel (kind of like an idler gear) away from the speed gearset to let the shutter run faster. It's bent, and as you try to change to speeds higher than 1/50 it's hitting against a flat spot in the speed setting cam that allows for slow speeds.

You can get to this pin easy enough if you are handy.

Take off the leatherette on the front of the camera.

Remove the plate that has the shutter button mounted in it. Watch for washers beneath it.

Remove the lens bezel (the part that has the speed and aperture wheels in it.) It has 5 screws around the perimeter, and then it will pull straight off. The flash sinc must be set at "M", and the self timer must be at it's "rest" position to clear the bezel.

Now you can see the actual shutter. Unscrew the front element, and beneath it will be a scalloped wheel, which is the threaded flange that holds the speed cam onto the shutter. It may have a set screw in one of the scallops. Turn it half a turn and then you can unscrew the scalloped wheel, pull off the thin plate beneath it, and you're looking at the speed cam. If you are looking at the camera with the bottom of the camera facing your chest, the pin I'm talking about will be at the 5 o'clock position. You can pull off the speed cam and very gently straighten the little pin.

>>You must support the arm that the pin is mounted in while you straighten the pin<<.

Also note that when you pull off the speed cam, the detent that indexes the shutter speeds will just be sitting there loose. Take it out so you don't loose it.

If you feel like going this far, but would like some pictures, write me and I'll email you some.

Ron, about the leatherette. Some Yashicas had a simulated leather type stuff that can be peeled off and re-attached. Some have a brittle plastic covering that looks like leather, but comes off like bits of potato chips. Sounds like you have the chip kind, and it can't be salvaged.

Getting to the point where the shutter is open so you can see the insides is fairly straight forward. At least, up to this point there are no springs to fly out of it. Everything will stay put except for the aforementioned speed setting detent. Just take pictures with a digi if you have one, and you can use them for reference.

You can safely cock and fire the shutter without the speed cam on the shutter too. It will let you see how things work. It will act as if it is set at "B", until you release the shutter release link, then it will time off one second and close.

When you go to replace the speed cam, you have to use a small screw driver to tension the leaf spring that holds the speed setting detent, then slip the speed cam over it and into any one of the detent notches in the cam. Use light pressure on the face of the cam and rotate it all the way to the "B" setting (clockwise) and then back all the way to 1/500 (counter-clockwise). This will let all the pins that run in the cam get back into their respective slots. Then you can put the face plate on and thread on the retaining ring (scalloped threaded flange). Put the retaining ring back on to the same position it was when you took it off, (make a mark on it for a reference when you first remove it).

This takes a lot longer to write than to do. Once the leather is off the front, getting to the point where you can see the inside of the shutter is about a five minute job. Goes back together almost as fast.

Four screws to remove the shutter release plate, five screws to remove the lens bezel, unscrew front element, unscrew retaining ring, lift off front plate and speed cam. That's it.

Good luck. Write if you need help.