The ACU-1000 no longer receives firmware updates for its first generation modules (CPM-2, DSP-1, etc.). There is a free firmware update available to turn the CPM-4 into a CPM-6 module, effectively upgrading the ACU-1000 into an ACU-2000.
The ACU-1000 can still be sent in for repair (following the RMA process). Though some older modules, if deemed unrepairable, will not be able to be replaced.