Should I recap my speakers? If so who can do it?

As for where to buy the parts, there are several really good sources. I tend to use Michael Percy Audio and Partsconnexion.

When I got serious, that is when I retired, I built a break-out box to test capacitors for speaker applications. My experiments (two alternative forced choice, single blind paradigm) showed that the most important variable is technology: film and foil is best alternative, then metallized, then other. Second most important is materials: among the metal foils silver is best, but prohibitive; copper almost as good; tin is cost-effective; aluminum can be problematic because of the connection between the wire lead and the metal foil. Among the insulating films, styrene is most neutral, teflon somewhat bright, polypropylene somewhat muted. Third most important is brand.

The best manufacturers are very open about the technology and the materials they use - they brag about it, and for good reason. You can profit from their openness.

I did my speakers with caps from Erse. VHQ metalized film. http://www.erseaudio.com/Products/PulseX
Very reasonable and I could not be happier. Excellent sound.
No need to change resistors. I would however, remove the FASTON connectors and solder directly to the board. Ditto if FASTONs are used on the drivers.

I beg to differ on the sand cast resistors which sound harsh compared to the inexpensive Mills MRA. Resistors do make a nice difference and improvement and for little money. Path Audio is best, but they are costly. Nice bang for the buck sound quality improvement with the Mills resistors. 

When it comes to crossovers, resistors should be wirewound, or paralleled film/foil types to get proper power rating. Stay away from metal oxide resistors at all cost!

My personal favorite are still the Mills MRA-12, but I also like Ohmite AG12.  

Rather than arguing about quality of parts. I think it is very important to see what kind of budget that James wants to use. I tend to be more frugal than others here and I’d hate to discourage him from an update. Even with some less expensive parts, he will hear a big improvement from the stock crossovers and really what it comes down to is what the person doing the mods wants to use.