tape echo bias head/circuit

[g1]

Have a Univox EC-80A with the bias head measuring open circuit. Would like to change it to the EC-80 arrangement which does not use a bias head. Any tips or suggestions for adapting the circuit would be appreciated.
Schematics here: http://music-electronics-forum.com/a...ord-ec-80a.pdf
and here: http://music-electronics-forum.com/a...cord-ec-80.pdf