Hi Raul,
It's been a while since I pulled to 707 out of the hanger but I did find a solution to this problem. If I remember correctly, the G/S problem is initiated when I used the doppler  and put the A/P in the NAV position. Before you disengage the AP, simple switch it to the NAV/LOC position, then disengage the autopilot ( or auto-land in NAV/LOC -APP) Then your G/S will function properly. Let me know if this works. If not, I'll fly my 707 and I'm sure it will come back to me.
Cheers,
Brian