Most likely the crappy economy is helping things along.
I think using and promoting repairs has definitely brought more in, but ya gotta keep changing up the game a bit. Others are advertising, and yeah I know about 0 budget for advertising, but people find others first for the obvious reason that they are easier to find.
For those not seeing the web site, the shop's hours are not evident. Lots of people are old school too. They are not being reached.
Right here at home, we could create some new biz cards, Pass a bunch of them out to the regulars and ask them all to hand them out to places where they do business. When you go pick up pizza, hand them a card, ask them to pass it on or put it up somewhere. Hell we could create fliers and pass em around, put them on windshields, etc. Lots of cheap and no cost ways to get the word around.
Exchange those business cards with your customer's biz cards and refer people to your customers. I've seen places where a container is placed full of business cards, and I know there;s a couple bulletin boards in the shop that could be placed in a viewable area.
I understand the worry's about a sign, but you can't do business with people who can't find you. They will go to the competition. They will not be treated as well.