Do you have a GE handset?
if so get the correct cable with the connector that connects to the SX controller and go in and check the settings.

you may want to check the settings in the controller, these are what they should be for this model, ONLY THIS MODEL:
Function: 36v 48v
1 16 16
2 60 60
3 20 27
4 255 255
5 15 15
6
7 80 80
8 255 255
9 35 35
10 255 255
11 0 0
12 0 0
13 113 113
14 24 16
15 36 48
16 130 130
17 135 135
18 149 149
19 255 255
20 255 255
21 30 25
22 183 183
23 50 50
24 100 100
25 0 0
26 5 5
27 0 0
28 0 0
29 0 0
30 0 0
48 30 40
49 0 0
50 0 0
51 80 80
52 30 40
53 18 18
54 0 0
55 0 0
56 20 27
57 35 35
58 30 25
59 0 0
60 15 20
61 70 70
62 60 50
63 0 0

make sure it is set this way.

and please go back and double check your wiring to the line contactor, trace these wires to their origins or destinations and make sure there are no pinched or chaffed wires that could be shorting somewhere on the frame.