If anyone cares....
From memory, in 2006 I bought my present razor; a Braun CruZer (I know, it sounds like a gay bar) which has done excellent service ever since. A while before that I'd had a Remington with 3 cutting heads, that wore the original foils through in less than a year and the replacements in about the same time, plus repeatedly giving me razor burn marks all over my cheeks and throat AND the batteries were already failing. The Remington was replaced with a super-cheap Braun 4615, but that wasn't an efficient cutter and when the charger developed a fault I bought the CruZer.
Last week the foil on the CruZer failed, breaking away all along one side. Pretty good after 6 years, considering they have a design life of 18 months. A quick hunt found a number of shops had the replacements available, but I eventually chose Amazon, simply because postage was free and I already had an account (message there, web marketeers). The bits turned up today, prompting this post.
What to do in the intervening time?
Well, I'd not thrown that Braun 4615 away. The problem originally was that the charger would only trickle charge, taking several days to achieve enough power for a full shave. Now since the rest of the razor worked fine I just plugged it in and left it for a couple of weeks before putting it away - it's best to store rechargeable batteries full than empty and one never knows when something might be needed. So out it came. There was enough remaining in the cells to let the motor turn slowly, so back on charge it went, with the charger apparently now working fine. I got 5 days of shaving from that first recharge.
Will I revert to the Cruzer now? Certainly - it's a better shaver in many ways. Will I fully recharge the other and keep storing it? Definitely. It's NiCad powered, so full charging & discharging are required, but that can also mean long battery storage life, as demonstrated, it was so useful standing in that it would be foolish to just ditch it.
BTW the CruZer is still capable of 7 days of shaving on a single charge. Pretty good after 6 years of daily use.