Capacitor Questions Re-capping Dahlquist DQ-20s

Joelv, If you can't find the exact values that you need I may be able to have them custom wound at ClarityCap factory. PM if interested.

Dave
ClarityCap North America OEM Sales

Look at the list of Solen and AEON caps, on page 6 of the
following catalog: (http://www.percyaudio.com/Catalog.pdf)
Most capacitors are manufactured to a +/- 10 or 20% tolerance.
If you call Michael Percy, he can match caps to within a 2%
tolerance, as well as find you the values you need. A very
helpful person.

You can parallel the closes values to make up 14.5uf =/- 10 % so you should be fine.

As for the smaller caps, tweeter caps? find some that are exact values, 3 3.3, 4.7, 5, 5.6uf are common values, do check out the different brands.

http://dahlquistspeakers.com/

15uf is fine and have them tested and sort for values closer to 14.5uf. Always better to bundle values coming close to 14.5 uf.

15uF is less than plus 10% of 14.5uF and would sound more coherent than paralleling caps of different values. Jon Dahlquist's claim to fame was always time and phase coherent systems. It would be a shame to compromise that, by mixing the time constants of differing caps. I'll bet Percy could find caps, in his inventory, very close to 14.5uF(if not right on).

Rodmann is right. Many do feel three 5uf caps would sound better however. Some pretty big dollar speakers use this method, but I have not compared.

Three capacitors of matched brand, capacitance and voltage
would share the same time constant, and should not result in
any aberrations. Another subject that might be of interest;
observe the outer foil of the caps you use, and orient them as
mentioned in point 3, of the following article: (http://www.audience-av.com/capacitors/a_applications.html) Another service that Percy offers, is marking the outer foils of caps he provides.

I'm not sure if you are wanting to upgrade the performance of your DQ-20s beyond original, or if you just want to get them back to like-new condition.  Sounds like you want to restore them back to like-new.
If so, have you talked with Dahlquist?  They offer rebuild/restore services and after conversations I've had about their crossovers, I would suggest you ask them if they would sell you the parts.  I have a similar problem with the fuse for my Dahlquist LP-1 Hi/Low Pass.
I see they offer a few Kits for the DQ-20 and the DQ-20i.  They're not into being inexpensive, though.  For the LP-1, they want $20 for a fuse & they spec'd out a fuse (1/32 A) that I can't find anywhere else. Nevertheless, I would give them a look-see if you haven't already.
http://www.regnar.com/home.html