I changed the subject to vs BSC 421 since I'm now able to scan more channels with the 421
Add to the list :
91W
3820 V 30000 @ 67%
4020 V 31250 @ 44%
99W
3810 H 3253 @ 56%
4080 H 22760 @35%
Seems to me that the channels that are on the edge of staying locked on the 421 are not locking when I put on the C1PLL
Keep in mind that you are using a 1M dish which is VERY undersized for C-band. Your dish is actually receiving signals not only from the satellite you are aiming at but also both east and west adjacent satellites as it is not 2 degree compliant.
What this means is that being more sensitive, your C1PLL LNBF could be receiving not only a higher signal level from the satellite you are aiming at but as well a higher level of adjacent satellite interference which would greatly contribute in not being able to scan and lock certain transponders.
In order to do a proper performance comparison between the C1PLL and the BSC421, a 2.4M or larger dish which is 2 degree compliant must be used.