Any choices for maint. on DCS products not UK?

I have very early models of Purcell and Delius (non firewire) I would like to be checked out. Delius was acting up yesterday in the way of information loss in certain frequencies. Cleared up when I toggled the input back and forth. Time for a checkup. Also considering upgrades on these units as well. Any places in the US specialize in this? May consider selling these so I would like to be sure they are solid for the buyer. Thanks in advance.