timing issues

[stuck1]

hey guys, new to the forum and have a problem that i coul use
some help on. have and 87 turbo with some timing issues.
19k on motor and i recieved the car with this problem. all
my timing marks line up cams and crank at tdc. when i jump the
diag connector to set timing and start the engine, i can't get
it to go to 10 degrees btdc. no matter how far i move the cam
sensor. when to sensor stops, that is 0 degrees tdc. wont go
any farther. i just cant figure it out. no vacuum leaks. new plugs
and wires. just wont work for me. any help would be much
appreciated.