Those look a little newer than mine were, my caps were all electrolytics and were replaced with Solens, i also replaced the cheesy double pot arrangement with 30 watt Violet Lpads. They were my first real Altecs, they catapulted me into several more pairs. I don't currently have a pair of the "Iconic" vintage 15 inch 2-ways, but a close and sweet deal on AS-101's would change that in a heartbeat. They have all the "soul" of the valencia or flamenco, but IMO, in a much more attractive enclosure. I would not hesitate to go the Solen and quality L-pad route again with another pair if i ever get them.

I really like the sound of Solens(doesn't mean that everybody does) as the series cap in the HF section of the network. You can save a few bucks by using Dayton/Bennic for the shunt caps across the woofer section, but in either case neither manufacturer makes a 21uF, so you'll have to parallel two to get the proper value. Solen doesn't make an 8uf even either, i think it's 8.2, but that difference is negligible and well within the 10% or more tolerance of the originals.

Just my .02................................