How to operate the shimano 21 speed shifter - Shimano Cycling

This YouTube video tells you how to lube the shifters, seems to be well rated: How To Clean Lube Grip Shift Shifters
You should also check cable/housing, however, as if they are corroded, kinked, etc. the shifters will also be hard to operate. Do not use grease to lubricate cables, though - only a light oil or spray lubricant. You can also just replace the cables.

I’m happy to help further over the phone at https://www.6ya.com/expert/donald_f2ed37026a3ac881

If you can't find with a search for st-ef40 diagram or on the Shimano site then it does not exist. Although not identical carefully disassembling the other shifter may give you enough insight.

I’m happy to help further over the phone at https://www.6ya.com/expert/donald_f2ed37026a3ac881

Contact local bike shop for assistance

Assuming that the normal set has been done properly, consider replacing the derailer. Could be bent or broken parts.

There's a used pair on an eBay auction right now ending 6d 09h (Sep 21, 201101:52:54 PDT) that you might be able to snag for cheaper than a separate right lever. Wait til the last 10 seconds and bid ONCE. Leave time to confrm the bid.

http://www.ebay.com/itm/SHIMANO-SORA-8-SPEED-STI-3300-BRAKE-LEVERS-DUAL-SHIFTERS-8x2-8sp-/200651614761?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item2eb7c4aa29

There are other models, too.

My $.02: I'd take the opportunity to switch to Campi Ergo (also available on eBay). The brake lever is ONLY a brake lever so you don't have to tip toe around it when shifting and ALL CABLES are hidden.

Schwinn doesn't make the shifter. Maybe Shimano? Determine the model and look it up at
http://techdocs.shimano.com/techdocs/index.jsp or the applicable manufacturer's website.

Look around here.

http://techdocs.shimano.com/techdocs/blevel.jsp

Mountain Shimano Tourney Shifters

http://www.parktool.com/blog/repair-help/chain-installation-derailleur-bikes

Go to http://techdocs.shimano.com/techdocs/index.jsp

Search in drop down list to go to all tiagra items and identify your particular components. Shimano are good at numbering their parts and you should find the number you seek on the bicycle component. You will usually be able to download an exploded parts diagram and service instructions. The service instructions are prefixed by the letters SI.

You must replace your shifter with one that is the same type, that is, if it is a six-speed shifter, you must replace it with a six-speed shifter. Also, if you have a Shimano derailleur, then the shifter you get must be a compatible type. Shimano uses a 2:1 actuation ratio, so you have to use a Shimano shifter or a SRAM 2:1 shifter (Attack, Centera or MRX models).
The only stupid questions are the ones we don't ask, friend. Look on eBay under bicycles for "6-speed shifter" and you will be able to find some really good deals.
When it comes time to work on your bike, go to Park Tool's website (parktool.com) and on the top right corner is a "Repair Help" link. You can select your topic by highlighting the part in question on the bike.

Hope this helps,
matt