Not necessarily.
I'm sitting here listening to a pair I actually own, have refinished the cabinets, have cleaned every connector, and have redone new grills for and they sound outstanding with the "stock" caps and resistors. I actually took measured the stock caps and they were all within a few percent of their rating. Do you have the manual that shows what caps go to what? If you need that, shoot me a PM and I'll email them to you.
Here's a quick breakdown....
Group 1 is a 2.2uf + .33uf + .33uf for the Emits hi-pass crossover. All poly caps.
Group 2 is 3.5uf and a 6.8uf for the dome midrange. All poly caps.
#3 and 4 are 600uf caps that are for the Watkins DVC woofer. Mine were within 2% of their rating. I wouldn't touch them unless they are way off.
#5 is a Poly cap used for the "mid bass coupler". Mine was within 3%. Didn't touch it.
#6 being the resistors that they are, generally don't drift too bad, Replace them if you want to, though. I didn't.
I cleaned the crud out of the pots which are the main problem with these like many other speakers. That made the biggest difference as they had sporadic control range. IF you want to spend money on replacing caps, I would do it for the Emits, dome mid and MB coupler but would leave the big 600uf caps alone. Unless they are off, of course.
Just my $.02 from a Quantum 3 owner.