Thanks for your answers.
Unfortunately, I'm still unable to make the tape load on my D8.
I'm using new batteries, the unit has been bought recently from Lighthouse Media Studios in South Carolina, USA. They bought it NEW 2 years ago and hardly used it during those 2 years (from what they said to me). I'm from France.
When I put the open/hold selector on open position, it usually doen't say "open" and doen't (slightly) open automatically. I have to open the unit myself.
When I put the tape in the D8, it usually doen't show "load". I have to activate the economical mode (hold function) then to place the open/hold selector on the mid position to make the unit try to load the tape. The loading ALWAYS fail. I tried to put the tape slowly, quickly, with the edge of the deck that has the dc plug facing the floor ... but it always failed. By the way, the lid is fully opened when I place a tape in the unit. (a soft click is heard)
If I hit "record" then "pause" buttons with the unloaded tape in the unit with the lid closed, the unit tries to load the tape : load appears during 4 seconds then a blank screen (1 second) and the screen finally comes back with 0h00m00s.
Also, it never showed a "blank" message on the screen.
If I use the "play" button, the screen also shuts off after 4 seconds of "loading" and comes back to 0h00m00s like when I hit the "record" button.
Should I try using other DDS tapes or maybe audio tapes ?