I have a Kenmore Model #15819141 and my power switch has broken. I can't seem to find a replacement part anywhere. Any suggestions?

https://www.shopyourway.com/questions/1129707

Web site above suggest 5186 is not the model number. Discussion suggest model number location on the sewing machine, and it may be 148.12190

Manuals for sale below may be of assistance:

http://www.kenmoresewingmanuals.com/kenmore_148_manuals/kenmore_148_manuals.htm

it's possible that there is a part inside the machine that could be broken, it would be a good idea to have the machine checked.

http://www.brother-usa.com/ModelDocuments/Consumer/Users%20Manual/UM_XL_5130_5232_5340_EN_208.PDF

Look up "darning" and it shows a feed dog cover so that means this machine does not have dropping feed dogs.

Now that that is out of the way... most machines have the ability to adjust the height of the feed dogs. But without seeing your machine I can't advise you. It might be better to go have the machine adjusted and serviced.

Has moving the lever felt mushy or really loose and wiggly lately? If so it's probably worked itself loose and jumped off it's path. OR if it is plastic it probably broken.

If it is definitely broken contact Sears parts for a replacement. If it is metal then you can get into the head area.... you can probably tighten the screw that holds it in place.

Good luck

try these sites, you'll have to email them about a manual
sewvacdoctor.com
a1sewingmachines.com

have you tried any of these sites

sewingpartsonline.com
sewvacdoctor.com
whitesewingcenter.com
sewingpartsdirect.com
sewingwarehouse.com
sewforless.com

as for the hand wheel not not being able to turn, it's possible that something could be loose or broken

you said it's been sitting for several years,, I would suggest that the machine needs to be serviced
by a sewing machine repair shop, where they can check the handwheel & find out why it won't unlock, & that the gears & inside the machine can be checked & grease & oiled & the timing check also

Sounds like your machine is in need of a good cleaning and oiling. If you aren't handy with taking apart things and getting them back together I suggest taking it to a sewing machine repair place. In the meantime you can try oiling any spots you can access. Use sewing machine oil, found at any sewing/fabric store and even most Wal-Marts.

If You have a drop in bobbin you will have to remove the hook and adjust the tension, however try adjusting the top tension before you remove the hook.

i have a older kenmore sewing machine model #148.19370