Worth repairing a Velodyne ULD-12 from the 90's?

It depends on what's wrong with it.

I recently had my DD18 repaired, had to have the amp rebuilt but it's back and as good as ever.  Glad I did it.  It was a few hundred bucks but it'd be very expensive to replace.  

I have the ULD-15, a MK I and a MK II. 

On the MK II, the foam fell apart. 

I bought a kit from these guys:

https://www.springfieldspeakerrepair.com/collections/diy-foam-surround-repair-kits

It was far easier to do the repair than I imagined it would be, as the cone tends to just center itself.

It works like new. 

there is a place in new jersey that fixed my servo board on my uld 18mk2.

https://www.ebcelectronics.com/

@waytoomuchstuff You mean that multi-purpose spray cleaner or a big block Chevy...?

Probably not and besides, most all the new subs come with an app that makes setup a breeze.

All the best.

@russ69 

"I don't think so, not a fan of down facing subs."

I've found that ugly woofers are more esthetically pleasing when they are down facing.

@sdberman 

"Not working" is a pretty broad description.  As @musicfan2349 suggests, refoam kits are very reasonable and CAN be a DYI project if you have a little patience.  If you have a non-working amp, you can send it off for repairs.  Can't imagine this being north of $200, including shipping. (We fix old stuff.  Not looking for additional work, but just a thought on repair costs). If it's not powering up, you might look for a blown fuse?

Sentimental value?  Who can forget "It's so fine, my VEL-O-DYNE?"

Your Father sounds like he had it going on, nice.

Market value? Working, its still a potent little model. Without a need for it your on your own.

Not much trouble shooting information in the ULD manual.

http://velodyneacoustics.com/pdf/uld/ULD-12Manual.pdf

George Meyer AV in Los Angeles CA has been and may still be an authorized Velodyne GmbH repair center.

https://www.georgemeyer-av.com

I purchased my first Velodyne subwoofer, a ULD 18 in 1984 replacing a sub from a Southern California Co. who designed a servo circuit with the sensor attached to a driver with minimal modification to the speaker. Velodyne’s David Hall proprietorially designed a driver motor around the servo resulting in faster reaction and loop timing with measurably lower distortion. The difference was not subtle. Still using DD Plus.

With the exception of Velodyne home subwoofer hindsight the down firing cabinet and room location suggestions remain an after thought for the home HiFi community, not so in the recording industry. I ran my ULD on its side atop two old Boogie boards located along the wall positioned within the rooms standing wave mode.

Good luck with it.

Most of these responses are just flat wrong. 

When I pulled my old RHLabs sub out of storage the surround on the driver was dust. Just a quick websearch led me to these folks:

http://www.theloudspeakerstore.com

I pulled the speaker and for a reasonable fee they repaired the speaker good as new. No need to ship the whole enclosure. 

Happy listening  

I don't think so, not a fan of down facing subs.

Sell for parts or buy another for parts to solve the issue. If you can't do the work yourself it might be best to sell for parts. Someone out there will need it.

That's what I figured.  Thanks. 

I would only repair if it has sentimental value.  Modern subwoofers are hard to sell and get repaired.  Older ones are heavier and will be more difficult.  You might find a vintage shop that would take it for parts or might have an interest in refurbing.  That would be your best bet