Series I Bridgeport will not change speeds

Hello all. I recently acquired a Series I Bridgeport which has a broken belt. I have read the manual, read through various forum postings and watched the videos. In all they say to run the motor down to its lowest speed, however I have noticed that turning the hand wheel has no effect on the speed of the motor (up or down). Additionally, all of the instruction is to use 2 of the lower cover bolts to compress the spring, however since the speed won't change the spring remains extended which will not allow me to get the bolts in.

Before I take it apart, is there anything I should be aware of? The HW video is pretty comprehensive concerning the top end tear down although I haven't looked at reassembly too hard yet.

Thanks in advance