Kenmore 158.17921 Need to know where to oil? machine sticks at times. Do not have a owners manual.

Try manuals on line.com or sheck out Youtube in how to oil a machine. :-)

Page 94 of the manual:

Kenmore 385 16221 Owner Manual Table Of Contents

FWIW, it is important to keep your machine clean and oiled for it to operate properly. Use ONLY good quality sewing machine oil and apply ONLY 1-2 drops every place indicated, approximately every 40 hours of sewing time.

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Are these the pictures you have?

KENMORE 385 12612090 Owner Manual Oiling The Machine Oil The Underside

Something you can do is slightly wiggle the handwheel (do not turn it in reverse). The handwheel should always turn toward you.
Look at the pictures and watch where metal rubs on metal that might match the picture and apply one drop of fresh, good quality sewing machine oil.

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If you look at the Oiling Instructions in the owner's manual, it has a picture of where the oil should be applied. Only one or two drops!! It should probably be oiled frequently--about every 8 hours of sewing time. Pfaff probably sells a sewing machine oil for your machine. Just tell them your machine model and they should know what you need. Do NOT use 3-in-1, WD-40, cooking oil, or the old stinky brown stuff from grandma's sewing basket!

I believe your Kenmore is an older mechanical machine. If so, how long has it been since you've given it a good cleaning and oiling? Mechanical machines need frequent TLC, otherwise the old oil turns into a glue-like substance and starts sticking things together, including your selector levers and dials. Give your machine's bobbin area a good cleaning with a soft brush to remove dust and lint.

Then, use ONLY fresh good quality sewing machine oil. Open the case top and free arm cover (if it has one--if it is a flat bed, tilt the machine back so you can access the moving parts under the sewing surface), gently handrotate the handwheel toward you, watch where metal rubs metal and apply 1-2 drops of oil. (Your owner's manual may have instructions for oiling and your machine may also have oil ports--little holes-- where oil should be applied.) Do not skip the feed dog moving parts. Also, there is usually an oil port behind the bobbin mechanism next to the case. Put a single drop of oil on the bobbin race. Do NOT oil plastic, rubber, or belts! Be sure to move the selector levers and dials and, if possible, apply a couple of drops to their moving parts as well. To help loosen things quicker, direct hot air from a handheld hairdryer into the internal mechanics of the machine. Repeat the oil/heat process until things are moving freely.

In the future, be sure to give your machine a thorough cleaning and oiling after about 40 hours of sewing use. A drop of oil on the bobbin race is good every 8 hours. If your machine sets unused, oil every six months to keep it operating.

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Perhaps the Owner's Manual will help:

http://homeappliance.manualsonline.com/manuals/mfg/kenmore/38515358.html?p=1

Be sure to use good quality sewing machine oil and white grease as explained in the manual.

P.S.--from the manual's instructions, it appears that you do not need to remove the face plate to oil your machine.
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Check this page for the manual, note that the manual can be scrolled to read. So you can get info from this site:

Kenmore 385 15212 Owner Manual Oiling The Machine Oil The Shuttle Area

they have a oiling machine info on sewusa.com website,,look under repair

Remove the top and bottom covers. Turn the wheel and put a drop of oil anyplace that moves and rubs.Also at the ends of each shaft. Open the side cover and oil the needle bar and all the parts inside that move and rub.Put a drop of oil on the hook.Do not put a good piece of fabric in the machine right after you've oiled it. Sew it off on some scraps that you can throw away.
sewman7

Manual Here: http://www.managemylife.com/mmh/lis_pdf/OWNM/1006108L.pdf