Vintage Hiwatt 100 with no serial number

[-maz-]

I purchased it 30 yers ago and it was already old.

But there is no type, model or serial number.

Any idea how to trace the year model?

[mhuss]

A clear shot of the guts would help us narrow it down. There's also date codes on the pots and capacitors:
http://hiwatt.org/dates.html#DateCodes

--mark