Good for you
Great find, congratulations. BAJA's advice on the filter is correct, keep the silver part dry but soak the bottom in Lime-Away or CLR, and I used a fingernail brush and pushed through the holes, got out TONS of ugly fine crap. Now, a two-second rinse under the faucet after each wash keeps it spotless. And it does a fine job, lots of lint.
I happen to have a Halo-Of-Heat service manual, up to DG700 and 701, only slightly before your machine. If it can be of help, feel free to ask--
Congrats on your new find, solid and responsible machines. And a matched set!