I guess you mean your Beocord 6500. If the drawer will not open, you can gently pull it out. The tape should be possible to lift up from the side closest to you.

The tape can become stuck by partly engaged tapeheads etc., if the mechanism stops mid-cycle. This typically happens when belts are getting worn, and wheels are slipping. Drawer out, from below, through the tiny holes, see if you can rotate the left flywheel/capstan by pushing it with a small screwdriver or similar tool. It should be rotated clockwise (seen from above). One rotation is usually enough to release the mech. It may be necessary to hold the flywheel using something else - a cottom bud or so - while shifting to the next push of the screwdriver, because the belt will have an "elastic" effect on the flywheel. Martin

That is good advice! Ki nd regards, Redfox.