Hi George,
Sounds like a similar issue I had with my 730. Read this topic for solutions :
You can start with the easy stuff first :
With a cotton swab and some IPA (isopropyl alcohol), clean the head and pinch rollers.
Problem not solved? Replace the pinch rollers. DCC musuem sells them, or 2dehands.be also has a guy selling new ones.
It’s an easy replacement. Just pop out the old ones with a flathead screwdriver, and manually push the new ones in. No need to take the whole tape drive apart.
Touch the housing of the deck regularly to avoid static electricity buildup between you and the deck.