I would run the diagnostics from the original grey disk for this system or down load it from [https://www.macintoshrepository.org/28403-all-apple-hardware-test-aht-apple-service-diagnostic-asd-disks|Hardware Test (AHT) & Apple Service Diagnostic (ASD) disks] as Apple so kindly removed all of the old T/N's and software from their site.
Thank Apple for forgetting all of the older systems still in service!