Replace Dynaudio woofers?

That being said the Xover is old and capacitors drying out for sure .

I just rebuilt a nice pair of contour 3.4  they sound much better then even their new30 model .

To be totally honest the Xovers in over 90% of speakers under $15k are not thst good of quality. I know for not only have I owned a Audiostore for a decade 

but learn8ng over 20 years ago on parts quality in Loudspeakers as well as electronics ,only 25% or Less goes into the complete speaker including all packaging this is a fact the rest R&D overhead and markup. 
I just rebuilt a pretty respectable Xover itwas $1500  but the end result sounded better then a speaker at 2x thecost  , if they sent me the Xover then it’s less monies 

and I just upgrade the resistors and capacitors , BTW Dynaudio use parts from their area such as The Very good Jantzen inductors , the resistors , capacitors not that good . If you email me  in c o d e I can show you picture examples .

go to humble homemade hifi capacitor test ,the exceptional Tony Gee has this capacitor guide as a loose reference ,  different drivers sound better with different capacitors and resistors , I totally recommend WBT connectors .Dynaudio drivers have not changed that much. The build quality excellent. In my 3.4 contours I rebuilt including Cardas best -0 Crystal 6-9s copper  Litz wire  sounds better then their new 30 model it replaced by a good amount I spent $1600 just in parts .

I may be selling these later in the fall in rose wood cabinets each driver has its own dedicated chamber these weigh over 90 lbs each with boxes . 

There is no chance you can build anything for $100  . I am speaking quality 

I have been dojng this for over 20 years , my standards are much higher 

having been into Audio for 40+ years, for example these white $2 resistors I use $30 each X4. Path audio ,much better detail ,clearer more open , if on a budget put in 12 watt mills resistors $12 each ,the inductors are Jantzen and good 

the white Mundorf are their lower mid grade Evo capacitors, Mundorfs Best quality are Black their Supreme line . Foil capacitors are better then sprayed conductors.

myself use the much more expensive Jantzen AlumenZ  capacitors ,

and Duelund tinned Copperfoil Bypass caps for the tweeters to complement the Jantzen ,I spent without the Upgraded Cardas wire $1300 just in parts .

that being said you can build a external Xover and use the Best Duelund capacitors 

depending on sizes 3x the monies, why don’t $50k speakers use top quality parts 

is all about saving $$ . I am just pointing out these from a 20 year+ point of expertise .  Just go to Humble homemade hifi capacitor test, the white Evo caps are respectable , and used by a lot of companies but rated roughly a 9

pThe best Duelund a 15,   Just get rid of the 4 -$2 resistors and put in all Path Audio resistors , and a .01 uf Duelund tinned Copper foil cap for the tweeter capacitor you will hear a solid increase in resolution and refinement for under $300.

I am just suggesting it’s your speaker I have been there done many combinations and still do for others ,all depending on budgets.