Any one ever replace caps or modify there Xovers

UH? Can't you just LOOK at it and draw the Sketch-o-matic?
The DCR for the inductor can be measured.....amp off and lift one leg.
The problem would be the inductor value. That, too, can be measured.

Start tracing wires.....and maybe take a few photos.

NOTE: I didn't actually say to go ahead and DO the mod.
Parts ain't parts. Caps have a resistive and inductive component.
Inductors? Resistive and perhaps capacitive as well.
Point being?
Changing parts is perhaps a little MORE complex than just matching values and warming up the old iron.
For higher end speakers.......they are 'voiced' which means that, theoretically, at least, parts are chosen for sonic goodness.....relative to the goals and design constraints.
I would gingerly approach crossover mods and be aware that more money doesn't necessarily mean better sound.
As a minor counterpoint to Shay, many designers and 'mod' guys will swear by the 'bypass' cap. Say...you need 20mfd. Well, get a couple 10s or even a single 20mfd cap. Maybe spend a bundle. BUT they will also throw a .01 across in parallel. Something about the HF passing thru more easily......and adding to the quality.
Just a thought.