Depending on where your locals come from, it may be ok for 99(s) and 103(s) to read zeroes, but 99(c) and 103(cb) should have signals across all non-n/a transponders. Is this a SWiM dish or standard Slimline/older dish (is there 1 or multiple wires coming from the dish)? Do all your receiver wires go straight to the dish or is there what looks like a splitter somewhere? Is there any possibility that the dish has been knocked around? (High winds, branches flying around, low flying geese, kid playing baseball, etc?) Unlikely since you still have 103(ca), but it's something to consider. More likely, if it's SWiM the LNB is bad, if it's standard Slimline, then it could be a bad LNB, bad multiswitch, or bad coax cable. I'd say it could also be bad B-band converters but the odds of all failing at once is slim to none.