14 ohm 7” midrange driver

8535 is about 14ohm at the crossover point for your speaker. 

I was just looking at the same for my ProAc Studio 200s.

Don't see my 6 1/2" mid-woofers, as they are also marked as 14 ohm.

Did you find if the 8 ohm were correct for your Response 3.8s?

The other option I was going to look in to was Millersound in Pennsylvania.

It looks like they may be able to rebuild drivers....from re-cone to re-wire voice coil maybe?

@foeraus

If you are handy with a soldering iron and software, use REW wizard to properly measure the driver impedance.  Otherwise get DATS V3. 

It drives me nuts to see people spending weeks on a problem the right tool could solve immediately.

I was fortunate to find a guy who could repair mine. 
He did great work and there is no inconsistency between the left & right speaker.

The speakers are still working today , quality work.

Outlier Audio, 773-844-1983

As I recall, I was not able to source replacement drivers and I reached out to a number of places.