Should I buy used Thiel CS5

But there are two smaller black ones with a middle hump and rounded ends that are similar shape to ELs

Possible, but the guy that stripped those xovers and posted the pics says they are plastics,
Those ones have "two little men" on them after I zoomed in on them, which I’ve never seen, and they seemed to have been bypased with poly’s
If they are bi-polars electros then yes change them as they are only a couple of dollars each.

Cheers George

I must also consider the first order crossover and the extra work that it places on drive units. No doubt there has to be some voice coils in those drivers that are near burnt after 30 years of use. I will have to call cohert source service to see if they have replacement drivers for the CS5. 

@jeffvegas, when making that call, you might want to inquire about availability and costs for upgrading to CS5i status, as well as about possible future upgrade possibilities. 

jeffvegas,

For a price point, I have a pair of CS5's that I bought for $2600 including delivery about two/three years ago.They are oak with the cream colored grills.

I had to replace one of the yellow speakers (largest of the three small ones) about  a year ago. Otherwise no problem except finding a good DAC to tame the tweeters which can sound sharp.

Thanks for listening,

Dsper

Other way around to me, the tweeter doesn’t need taming, it’s oil can resonance is well above 25khz and low in amplitude
The dac/pre/amp has to be good, so the tweeter doesn’t show up their HF deficiencies.

There is the possibility though that the tweeter if "ferro-fluid" cooled, this will go hard with age and cause non linear sound distortion issues.
B&W need their ferro-fluid replaced around this same age https://www.speakerrepairshop.nl/en/instructions/replace-ferrofluid-in-tweeter/c-36

Cheers George