PSE-HL1 info sought

Does anyone know where to find any prints for troubleshooting one of these pre amps?
The address for PSE is below: Professional Systems Engineering, Inc. Incorporated since 1973 9755 Hamilton Road Eden Prairie, MN 55344-3424 TEL (612) 943-1677 FAX (612) 943-8730 Email: WEB@PSE.COM

All over Audioasylum. Do a search for PSE in the amp/pre-amp section. Supposedly the original owner is helpful. I love my Studio IV amp!
I located Dean Klinefelter in Minnesota and still seems to be involved in his products as he offered troubleshooting help;Phone number is 763-295-1710 for anyone who may need it as well.