To be honest I've not done any maintenance on my 25y oldish Beyerdynamics beyond jury rigging a fix to the support of the left earpiece which lost a critical sm

To be honest I've not done any maintenance on my 25y oldish Beyerdynamics beyond jury rigging a fix to the support of the left earpiece which lost a critical small piece of plastic in a minor impact. Yes - the pads could use a replacement but it's not critical. Yes, they are a bit grimy. But work well :)