These days, most music isn’t leaping off the shelves, it’s being digitally downloaded. CDs have gone the way of other past technologies like cassette tapes and… well actually, records are staging a comeback. It’s small in terms of overall numbers, but a significant industry-wide trend.

Last November, The Guardian noted that U.K. record sales hit an 18-year high. Megan Gibson at Time reports that Nielsen Soundscan’s numbers show 9.2 million vinyl records sold in the U.S. last year, a 52 percent increase over 2013. Vinyl fans contend that the sound of records is "richer, warmer and clearer" than digital downloads Gibson writes. The nostalgia factor also attracts people — the top-selling records hint that the buyers aren’t older folk looking to remember good times, but young people looking for vinyl versions of their favorites.

But there is one problem. As NPR's C.J. Janovy reports: "The machines that press vinyl records are decades old, and no one's building new ones, so keeping up with increased demand is hard." In fact, record manufacturers are having a hard time matching the market.

Making a record requires several steps. First, electrical signals from a music recording are etched into a lacquer disk with an aluminum core. Then, at a production plant, that lacquer is coated in silver and nickel to create a metal master. The master serves as a stamp for the actual vinyl records. ​

The record cutters that etch the lacquer and the hydraulic presses that push stamps into vinyl are all in high demand. Chad Kassem, proprietor of Quality Record Pressings, a vinyl pressing plant in Salina, Kansas, told NPR that the first presses he found were in bad shape. Janovy reports:

There are about 16 record pressing plants now operating around the country, and Kassem says it's an arms race to find any remaining presses that aren't already being used and get them back into production. He hit his latest motherlode in Chicago, where he discovered thirteen rusting presses owned by a guy named Joell Hays, who runs a rehearsal studio and bought the abandoned presses on eBay a decade ago, thinking he always wanted to make records.

The struggle is echoed at other record factories, Neil Shah at the The Wall Street Journal reports:

Record labels are waiting months for orders that used to get filled in weeks. That is because pressing machines spit out only around 125 records an hour. To boost production, record factories are running their machines so hard—sometimes around the clock—they have to shell out increasing sums for maintenance and repairs.

Though record sales are up, they still only represent two percent of U.S. music sales, Shah writes. That makes investors unlikely to pour money into updating the machines needed to make more vinyl.

And though music aficionados are clamoring for vinyl, turntable sales are not getting a similar boost, notes DeVon Harris for Quartz. He writes:

In an increasingly digital world, there’s not only charm and soul in the retro sound of wax, but it’s also found in the 12” physical art that comes with them. The further we dive into the digital, virtual world, the more ironic and iconic the physical manifestation of music (and information for that matter) becomes.

So apparently, some people aren’t listening to the records, they’re looking at them. If that’s the case, than an industry struggling to keep up with demand will only make vinyl more precious.