It is actually the foot of the machine that I would like to raise in order to sew bulkier items

Could be mis-threaded. Remove all the thread from the machine. ALWAYS RAISE the presser foot and rethread from the beginning. If it still will not stitch, you may need to take it for service.

Please expand your explanation of what exactly the machine is or is not doing. We can't begin to help without more information.

HINT: remove the top thread from the machine. ALWAYS RAISE the presser foot and rethread from the beginning.

http://www.threadsmagazine.com/item/4302/understanding-thread-tension/page/all

http://ohyoucraftygal.blogspot.com/2013/10/sewing-lesson-10-how-to-fix-tension-on.html

http://www.threadsmagazine.com/item/44844/how-to-achieve-ideal-sewing-machine-thread-tension/page/all

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Tension works pretty much the same on all domestic sewing machines.

HINT: ALWAYS RAISE the presser foot when threading the top thread!

http://www.threadsmagazine.com/item/4302/understanding-thread-tension/page/all

http://www.threadsmagazine.com/item/44844/how-to-achieve-ideal-sewing-machine-thread-tension/page/all

http://ohyoucraftygal.blogspot.com/2013/10/sewing-lesson-10-how-to-fix-tension-on.html

Are the feed dogs actually raising, moving, and dropping (raise the presser foot and hand-rotate the handwheel and watch how the feed dogs are moving)? If not, check to see if the stitch length is set well above the zero (which means it sews in place)? Perhaps the presser foot pressure is set too firm and is preventing the fabric from moving under the foot.

Perhaps the manual would help:

Empisal Overlocker 760C Empisal Sewing Machines

On most machines, it is important to ALWAYS raise the presser foot when threading the machine (although the instruction manual says to raise the presser foot only to pull the thread tail under it). Be sure to give the thread an extra little tug when going through the tension disk to seat it properly. Be sure to thread in the order as specified (Upper looper, Lower looper, Right needle, Left Needle). If the machine messes up, it is usually a best policy to remove all the thread and rethread from the beginning. Threading out of order will almost guarantee failure!!!

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With the issues you are experiencing, it may be wise to take it for service.

Even though the feed dogs are raised, are they actually moving forward and back as you stitch (remove the thread, raise the presser foot, rotate the handwheel, and watch the feed dog action)? Check that the stitch length is set long enough that the feed dogs will be moving the fabric rather than sewing in place. Another thing to check is whether there is a pressure adjustment for the presser foot. If you are sewing light weight fabric, sometimes the pressure needs to be increased so the feed dogs are able to grab the fabric.

As for the machine running on, it could be a multitude of issues, ie the foot control, electrical... This may be something that a professional should evaluate.

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check for broken drive belt that works the bottom shaft in the machine
have a sewing machine service center service it

Hmm. Raise the foot with the presser foot lever. You have to raise the foot up to get the fabric under the foot in order to see.

Yes indeed, it is possible--sounds to me like a screw worked itself loose. However, I would purchase the service manual for your machine. As a bonus, it tells you how to make all kinds of useful adjustments.

Go to Sewing Parts Online and do a search under Singer Service Manuals; if they don't have it in stock, call or email them and they will be happy to order it for you. Generally takes two weeks to get it in stock.

Are you pulling the presser foot all the way up. Most machines, stop when you raise the foot, but then you can raise it higher but putting more upward pressure on the foot raise lever, the foot will go higher. Give this a try. Thanks for using Fixya!