How I fixed my MFJ Antenna Bridge

At this point, the title is a bit optomistic. A) I haven't fixed it yet. B) I'm not sure what's really wrong yet. But I thought I'd create this log of my floundering.

Operational test.

1. Is the resistance calibration of the MFJ accurate?
A. Connect antenna to MFJ.
B. Set band switch to C range.
C. Turn on ICOM 706 receiver and set for 10.110 MHz.
D. Turn on MFJ and sweep frequency until MFJ oscillator can be heard in 706. (706 reading: 10.100; MFJ reading: 10.5 MHz.)
E. Calibration chart on back of MFJ says that 50 ohm resistance is "C 1/2" on the resistance dial. Set resistance dial for C 1/2.
F. Tune antenna tuner (MFJ Versa Tuner) for maximum dip on the MFJ Antenna Bridge meter.
G. MFJ Versa Tuner readings: Antenna 3; Inductance D; Transmitter 4.
H. Disconnect antenna from MFJ Antenna Bridge and connect to ICOM 706.
I. Read SWR on ICOM 706: 1.1:1.
J. Conclusion: the "C 1/2" 50 ohm setting on the MFJ Antenna Bridge is pretty accurate. Using the antenna tuner to dip the Antenna Bridge's meter seems to produce an Antenna Tuner setting that is pretty close to 50 ohms.

2. Is the frequency dial on the MFJ Antenna Bridge accurate?
A. Test by listening to the oscillator of the Antenna Bridge.
B. Readings:
15M: Can not hear oscillator.
17M: Can not hear oscillator.
20M: Can not hear oscillator.
30M: Actual: 10.1; Reading: 10.5 MHz
40M: Actual: 7.0; Reading: 7.7 MHz
80M: Actual: 3.6; Reading: 3.65 MHz
C. Conclusion: B range is fairly close. C range is reading about 500KHz high. D range doesn't seem to be oscillating.

I've got a schematic for the MFJ 204B; but not one for the 204. There seems to be substantial differences. The 204 only has two transistors; the 204B has 4. The 204 has 4 bands; the 204B has 5. I need to find a schematic for the 204. I think I'll drop a line onto the QRP-L website.

WA5PSA