Vintage Machines....
I've not heard of an ASEA before, so i'll trust Matt's judgement on that one!
What sort of age machine are you looking at getting?
When i speak of old machines i usually refer to 80's ones, but some on here do have much older models. The main reason i stick with 80s machines is theyre ones i remember from childhood, as i'd imagine is the case with a few of the guys on here.
Miele have always turned out good quality machines, though i guess second hand supply is quite thin on the ground as many people keep Miele's till they completely pack up. People seem to value Miele appliances alot more than other vintage ones, so therefore something like a house move where a Miele appliance is taken by its owners might result in most other machines being left behind. If you can find a Miele then go for it.
Another good option is one of my favorites, the 80's - early 90s Zanussi offerings. These are not everyday appearances on eBay etc, but you should find one of the younger 90s models at least once a month online. Many are 1000rpm spin & seem to spin nearly as effectively as my Parents 2007 Zanussi with 1400 spin, so you shouldn't feel like youre missing out on modern features, but still keep reliability & longevity that's typical with older machines. 80s machines (identifiable by their metal drum paddles) tend to spin more quietly than the sometimes unbalanced 90's machines (pictured below), which have grey plastic drum paddles. Either way they're a better bet for longevity than a modern machine.
Hotpoint's 80s/90's machines are still around in fair numbers & can be a good option too. My only point to note with Hotpoint is the lack of removeable fluff filter, meaning any fluff or coins etc can make their way further into the machine & on my Mum's 80's Hotpoint if this happened, the blockage would result in it draining water all over the floor. Not sure if this is characteristic with these machines, but it's obviously not ideal if youre on the 6th floor of a heritage building!
For maintenance, Matt said pretty much all i would've said, so a hot wash (60c or above) at least once a month, use of powder instead of slimey liquids, observation of the machine to make sure it all sounds as it should, that sort of thing. It's also important not to get frustrated by the slightly smaller drum sizes of older machines and try & cram them full, as Matt mentioned.
I believe Haynes, who make car manuals, also do one for washing machines but i suspect it'll be quite general advice because it focus's on washing machines as a whole and not a specific make of machine. I've seen them on the shelves with other Haynes manuals in Motorists Centre's, so maybe have a quick flick through one & see if it looks a worthwhile purchase.
Hope that helps a little,
Liam.
