L-39C RMI GC mode can not be returned after testing

[EcceHomo]

When using the test switch on the PU-26E panel, the RMI rotates to 0 or 300 degrees and the compass mode switch is in the GC. The RNI will not return to the position it was in before the test. This situation does not match the manual.（“The test switch verifies the correct operation of the GMK system in the MC mode. The test can be executed after terminating the GMK starting process, which lasts 3 minutes in MC mode or 5 minutes in GC mode. When the· test switch "CHECK" is moved to 0 (zero) position, the RMI compass card shall rotate to position zero degrees, when in 300 degrees position the compass card shall indicate 300° heading. The allowable indication tolerance is ± 10 degrees. The compass card repositioning shall be accompanied by illumination of the gyro drift indicator on both the GMK control box and front control panel. When the test switch is released to its center neutral position, the HSI compass card shall rotate back and indicate actual heading.”）