tascam Porta 02mkII- newbie problems.(HELP!)

[Welkinchild]

Good morning to y'all. I'm new here on this forum and I would be grateful for some advice and help concerning my tascam porta 02mkII.

Since I'm short on cash a purchased the cheapest porta I could find which happened to be this one.

The problem is that when I record something on it there's a "hissling" noice and the stuff that I try to record is almost un-hearable even if I turn the volume up on the amp.
The equipment I have plugged in is, of course the porta, an old vintage Tandberg amplifier from the 70's and a 90's double cassette deck as master.
One problem is that my amp only has three connections and thereby I cannot plug in both "tape out to rec in" and "play out to tape in" since I only have a single "tape" connection. Maybe because of this only one of my speakers sounds though both ears on my headphones work. Might that be the problem?? Do I need a new amp??
Concerning the master deck I don't even understand the use of it since beside plugging it in, it isn't mensioned in the users manual.

Besides this let me add that the recording has simply been done via a microphone and not plugging a guitar directly into the porta. (If that information is of importance.)
What do I need to do to make my recordings work? Could anyone give me an alternative users guide perhaps?

Best regards!!