Stop what your doing! I bout crapped when I saw your video.
First thing I noticed was the wine your hearing is your belt burning up.
The tape is so bad it is stopping your motors. I have seen this before.
Also what I think i saw was when you hit play in that video I dont see your pinch roller ingaged and the tape lifter ;probably didnt go up at all to let the tape make contact on the heads like they should.
To check this out leave the tape off of the machine and lift the right tape guide. Then hit play and see if your pinch roller goes up to the capstan shaft.
That will tell alot right there. Its common for these old machines to get gunked up at that area and they need a good cleaning inside and lubed to work correctly.
Try that and let us know what happens