Originally Posted by
Pat M. 
If you have a machine that has a needle that can be shifted around, move it to the 1/4" site. I measure from the right side of the foot to the needle and then move the needle to where the 1/4" would be. Also, do you have any lined 3X5" cards? The lines are 1/4" apart and I use them for measuring where the 1/4" is. Put you needle on one of the lines and look at where you sewing should be.
This is the best advice......since you can't move the needle, just figure out how to place your fabric through. I've managed to identify a specific location ON THE PRESSER FOOT because I too don't want to have to remove any guides to get to the bobbin. Good Luck!
Or another way to say that:
Using a 3 x 5 lined index card -
If your needle does not move - or only has left, center, and right positions:
Put your needle on one of the lines
Note where the line on the card is to the right of the needle on the foot
That is where the edge of your fabric should be
If your needle position can be moved teeny amounts:
Put the edge of the presser foot next to a line on the card
Move the needle so that it comes down on the line to the left (if you are going for scant - then so it's a teeny bit to the right of the line.
After figuring out where 1/4 inch is on one of my machines, I just make a mental (or sticky) note to myself - I really don't worry about a 1/4 inch foot or marking my machine.
However - if your machine is feeding the fabric very wonkily - I agree with the others - there might be something wrong with how the feed dogs are operating.
If you are going