I have an Olympia Progress manual typewriter. It seems to be in good working order, well oiled and good action in the keys, except the carriage won't advance when I type. I don't believe the carriage is locked because I can move it using the release button on the right side (although i can't move it with the tab lever on the right). What am I doing wrong?

I've seen one on an olympia typewriter. Like a switch on the left side of the machine next to the numbers line. Your problems could be Lock is bent, not connected fully, needs cleaning, oiling.
http://www.ebay.com/gds/How-to-Fix-a-Royal-Typewriter-/10000000205719319/g.html
This link may help. Some of the fix-it advice. Pay attention to carriage won't move paragraph. Check library for possible owner manuals, repair manuals.
Just found this link that may offer more help.

http://www.vintagetypewritershoppe.com/vintage_typewriters_22.html

is the left margin set at the point it stops if so reset it

Laura, are you sure ribbon is in the proper guides and position, if they are, slam the carriage back and forth a few times to un stick the position er.

The carriage is touching the cavers it need the flat rubber washers that are between the case and the frame look at the bottom of the typewriter remove the screw slip in a new washer and replace the screw do the same on the other side

Assuming that your Typewriter is non electric spray WD40 on all the mechanical pivot points especially in the segment where thr type bars swing.

DickyO

Usually when this happens part of the case or carriage is loose or bent. Move it back and forth and try to see what it is dragging on.

DICKYO

IF THE CARRIAGE IS NOT MOVING LEFT OR RIGHT, CAN YOU PUSH THE CARRIAGE TO THE RIGHT OR LEFT??? OR IS IT COMPLETELY STUCK. YOU CAN TRY CLEANING THE SILVER SHAFT THE CARRIAGE SLIDES ON AND LUBRICATING THE SHAFT WITH A LIGHTWEIGHT OIL, WHEN YOU PRESS THE KEYS DO THEY WORK.???

Mant portables have a lock to hold the carriage in place while in the case, on the rt. or left sides below the carriage.

Hope this helps
DickyO

YEP, MOVE THE PAPER FEED SELECTOR TO NUMBER 1

Hi..sewing machine is ok, a little too light but ok. Move your margins all the way out so that you carriage can move its full length.
If you look at the underside of the carriage you will see what they call Rails. These are tracks in which the ball bearings reside. 4 or 5 drops of oil on these and the bearings will be lubed. I use a little heavier grease not oil, but light oil. Too much oil is worse than none.
I think you problem is in the carriage return clutch..something that should be handled by a Pro.. Too many parts, springs and broken adjustments for the layman. Some times you can spray 1..I repeat 1 small shot of degreaser on the carriage return clutch (located on the right side, middle of the typewriter. Usually has a fabric band winding around it.
If not a Pro can help you..
Hope this helps.
Squipps