THE CLOTH DOES NOT FEED WHEN I CHANGE FROM A STRAIGHT STITCH

Change from a free-motion foot to a straight stitch or zig-zag foot. Raise the feed dogs. Adjust the width and length stitch selectors to your preference.

it sounds like the machine needs to be checked to see if there is a problem with a part inside the machine

you can't sew a straight stitch without the feeddogs being in the up position, or it could break a needle and damage the machine.
so when the machine says put the feed dogs up it telling you
it can't sew a straight stitch with out them up

Why don't you download the manual which will tell you everything you need to know? get it here. http://sewingonline.co.uk/library/JONES-VX-950.html

there is a couple of things to check:

What stitch length have you got the machine set to? Should be 2.5 for a normal straight stitch - how you set this will depend on the make and model but most machines have some way to adjust the stitch length and width.

Or are the feed dogs lowered? this is sometimes a slide or button on the front base of the machine, sometimes a slide at the back of the free arm, again, it varies between machines. You may need to refer to your machine's manual to establish how this is controlled - you lower feed dogs for things like free motion embroidery so if your machine is computerised with lots of stitches it may even make this adjustment automatically when you choose a free motion embroidery stitch. If that is the case then changing it back to regular straight stitch should return the feed dogs to normal function.

If you raise the pressure foot, and manually turn the flywheel towards you through a couple of stitch sequences can you see the feed dogs raising and falling? If you can't see this happening at all and you are sure that the feed dogs are engaged then it is possible a drive gear in the free arm has failed in which case, you'll need to take the machine to a serviceman.

As to your question about leather, the 6460 has a special stitch for sewing leather. Select Colormatic cam C and install in the cam hole at the back of the machine. To remove/add a cam turn the upper left hand dial on the front of the machine to the small dot. This disengages the cam. Gently remove the cam by pulling straight out from the back of the machine. Install cam C straight in, ever so slightly twisting it back and forth into the hole to find the sweet spot. You'll hear a click when it's all the way in.

To use Viking's leather stitch, turn the upper left dial to the color yellow. (Note: The slash line on the upper left dial is a stop. You can't turn past that point. Go in the other direction to get to the icon or color you want.) Turn the upper right and bottom right dial to yellow also. The upper left dial is what selects the particular stitch on the cam, the leather stitch in this case. The upper right dial selects stitch length, and the lower right dial selects stitch width. You can move the right dials within the color range. Experiment on a scrap of cloth to get the stitch size the way you want it. The leather stitch looks like a straight stitch with a block style edging to the right of the straight stitch. This is supposed to give a stronger stitch to the leather rather than a straight stitch by itself.
If you don't have the manual for your machine: Select which of the eight cams you want to use. All the cams are removed/installed by turning the upper left dial on machine front to the small dot. At the rear of the machine, pull/insert cam straight in or out and twist slightly as you push in or remove to find the sweet spot. Move the dial away from the small dot to lock the cam in.
Turn upper left dial to stitch type you want and match the other dials to that same color. Upper right controls stitch length, lower right controls width. Bobbin tension is controlled by the dial at front left of the machine, above the needle.
Cams A-C are the workhorse cams and the rest are embroidery stitches.Straight stitch, button and stitched zig-zag will work on any cam. These stitches do not rely on matching a color code. To use those three: To select straight stitch, on the upper left dial, choose the icon that looks like a buttonhole with a zig that trails off to the right. Select stitch length on upper right dial and turn the lower right dial to zero, going by number rather than color.
To select stitched zig zag, turn upper left dial to the broken zig zag icon (to the right of the straight stitch icon). Select stitch length and width.
To move the needle to the side for buttonhole stitching or other times when you want the needle off center, turn the upper left dial to the button icon. If stitching a button hole, set stitch length to zero and lower right dial to desired stitch width. Push in the small white button that's beneath the lower right dial in order to prevent the feed dogs from moving the fabric forward. Pushing that button in is also handy for putting cloth under the foot before sewing as it prevents snagging and is used for tacking.

So is the stitch length now back on 2.5 for a normal straight stitch?

Or have you perhaps put it into a buttonhole sequence or something where it is sewing in the same spot.

Or have the feed dogs been disengaged accidentally, this would also mean no forward motion during stitching. Can you run it slowly, no thread, no presser foot and see if the feed dogs are going through their normal up and backwards movement to check this?

Have you got the manual to trouble shoot and find how to renegage the feed dogs if this is the cause. Sometimes it is a slide mechanicsm on the free arm or at the back of the main sewing area.

Check to see what pattern is selected. Be sure it isn't the buttonhole.Select straight stitch.Move the stitch length setting to 4.Turn the handwheel and see if the feed dogs move forward. Press the reverse lever and see if they move backwards. Select straight stretch stitch and turn the wheel to see if the feed dogs move forward and backward.Check the presser foot release on top of the machine and make sure there is pressure on the foot.
Sometimes the reverse assembly on this machine stops working because it has the wrong type of grease on it and it turns into a hard gummy mess that won't let it work.
sewman7

Make sure the feed dogs are up properly. Under the arm of the machine, at the front, there is a dial. Turn it towards the picture showing jagged teeth as far as you can.

You can do all of these stitches by using different combinations of your stitch selector, stitch width and stitch feed knobs, for instance, on the panel I can see on your machine:

http://www.jo-ann.com/joann/product/images/52659.jsp?CATID=cat3122&PRODID=prd11333

Stitches 1, 2 & 3 are straight stitches, centered, left and right. Really basic stuff, not different stitches at all. 4,5,6,7 & 8 are zig-zag stitches of different widths. 9 is the widest zig-zag (no. 8) on a finer stitch length, etc...

I think you should try and get an instruction manual for your machine. After a lengthy search of my usual manual sources, I've determined that that this may not be so easy. I think you should contact White on their 800 number and let them try and help you... 1-800-331-3164.

If you found this helpful, please vote generously as I receive nothing other than acknowledgement for my time.