Grundig had a spin-off company making good quality test equipment. It was expensive kit though. Van Draper Electronics aka Digimess is the same product line under a new name. I assume Grundig sold off the test equipment branch when they suffered financial difficulties some time back.
Pictures of my PSU internals attached.
I also own the Digimess FG100 20MHz function generator that uses a MAX038 as its core ....VERY NICE
The function generator was also brand new with shipping damage. The mains transformer is a PCB mount type and a bump in transit had broken the primary winding at the point where it was soldered to the PCB pin. A bargain at GBP25
Digimess sell new and ex demo units on eb*y. I noted that they sold returned units as spares or repair at bargain prices. They seem to have realised that they were selling the faulty equipment too cheaply though, and prices have risen. When I bought my two units I was told that the company considered the cost of investigation, repair and resale as Grade B returned stock uneconomic, hence the bargains for me to buy direct from Digimess.
PN300 manual and brochure attached. I have the price list for 2005.....the PN300 cost GBP629 (US$943) +VAT +delivery.
Note that the distortion in the pictures is just the wide angle lens on my camera.
EDIT: DIGIMESS will supply a service manual for any of their equipment but you have to pay for it.