As the other two indicated, there are two main causes for this. Bad transistors or cold solder joints (usually on the header pins for the transistor connections.
You should reflow the solder joints on the headers and any other joints that look suspect. Especially do J700 since that is the connection for the X deflection transistors and you have what appears to be deflection collapse on the X axis. I know it seems backwards, but the monitor is rotated vertically on tempest.
Also, you can easily test the transistors with a digital multi-meter on the Diode setting. Unplug P700 (cable connector) from J700 (header on deflection PCB) and test on P700 pin side with the following tests and verify the results against the ones listed. Any results that are out of the range listed likely indicate a bad transistor that needs to be replaced.
Good Luck,
-VJ
NPN (2N3716) Test on connector at Pin positions 1, 3, 4 of P100, P600, P700
===========================================================================
Test #1
-------------------
Red -> Pin 3
Black -> Pin 4
Result: .45v to .9v
Test #2
-------------------
Red -> Pin 3
Black -> Pin 1
Result: .45v to .9v
Test #3
-------------------
Red -> Pin 4
Black -> Pin 3
Result: Open
Test #4
-------------------
Red -> Pin 1
Black -> Pin 3
Result: Open
Test #5
-------------------
Red -> Pin 1
Black -> Pin 4
Result: Open
Test #6
-------------------
Red -> Pin 4
Black -> Pin 1
Result: Open
PNP (2N3792) Test on connector at Pin positions 5, 6, 7 of P100, P600, P700
===========================================================================
Test #1
-------------------
Red -> Pin 6
Black -> Pin 5
Result: Open
Test #2
-------------------
Red -> Pin 6
Black -> Pin 7
Result: Open
Test #3
-------------------
Red -> Pin 5
Black -> Pin 6
Result: .45v to .9v
Test #4
-------------------
Red -> Pin 7
Black -> Pin 6
Result: .45v to .9v
Test #5
-------------------
Red -> Pin 7
Black -> Pin 5
Result: Open
Test #6
-------------------
Red -> Pin 5
Black -> Pin 7
Result: Open