There are some things you buy that last a few years before you ultimately replace them having either fell apart or technology has moved on and there's those that you keep and this is one.
I've had these Sennhesier HD560 II "Ovation" headphones for a good while having been introduced in 1991 but in the intervening years a lot of work was needed on them.
Starting with the leads to each headphone, the red right hand plug had become badly frayed at that plug end and needed replacing as the sound just cuts out.
The connections are actually on a plug and with a pair of pliers, you can pull them out and I was able to get a replacement lead set that also had better quality oxygen free cooper and gold plated connectors and have them fitted which solved that problem
This part, the centring insert and foam inner pads was a bigger problem because the foam inner pads had chemically become unstable disintegrating into a sticky powdery mess so not only had the pad fell apart, it had left deposits on that insert that needed to cleaned off.
I ordered some generic circular pads for them and inserted them and then refitted the outer cushion pads having given them a clean.
They now sound a little more open and deeper than they originally did which baring in mind at the time these were very expensive new,now not only have they been restored but are better than ever.