c7000v2 same 2 channels will not lock

my c7000v2 will not lock on channels 14 and 15. Any thoughts, comcast support was useless

Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 37 621000000 Hz 2.9 dBmV 39 dB 0 0
2 Locked QAM256 21 525000000 Hz 2.5 dBmV 38.5 dB 0 0
3 Locked QAM256 22 531000000 Hz 2.6 dBmV 38.8 dB 0 0
4 Locked QAM256 23 537000000 Hz 2.5 dBmV 38.8 dB 0 0
5 Locked QAM256 24 543000000 Hz 2.1 dBmV 38.8 dB 0 0
6 Locked QAM256 25 549000000 Hz 2.4 dBmV 39 dB 0 0
7 Locked QAM256 26 555000000 Hz 2.4 dBmV 39 dB 0 0
8 Locked QAM256 27 561000000 Hz 2.5 dBmV 38.3 dB 0 0
9 Locked QAM256 28 567000000 Hz 2.6 dBmV 39 dB 0 0
10 Locked QAM256 29 573000000 Hz 2.8 dBmV 38.9 dB 0 0
11 Locked QAM256 30 579000000 Hz 2.8 dBmV 38.9 dB 0 0
12 Locked QAM256 31 585000000 Hz 2.5 dBmV 38.7 dB 0 0
13 Locked QAM256 32 591000000 Hz 2.6 dBmV 37 dB 0 0
14 Not Locked Unknown 33 597000000 Hz 0.0 dBmV 0.0 dB 0 0
15 Not Locked Unknown 34 603000000 Hz 0.0 dBmV 0.0 dB 0 0
16 Locked QAM256 35 609000000 Hz 3 dBmV 36 dB 22 0
17 Locked QAM256 36 615000000 Hz 2.7 dBmV 38.8 dB 0 0
18 Locked QAM256 38 627000000 Hz 2.1 dBmV 38.6 dB 0 0
19 Locked QAM256 39 639000000 Hz 2.1 dBmV 38.2 dB 0 0
20 Locked QAM256 40 645000000 Hz 2.2 dBmV 38.6 dB 0 0
21 Locked QAM256 41 651000000 Hz 2.3 dBmV 38.8 dB 0 0
22 Locked QAM256 42 657000000 Hz 2 dBmV 38.6 dB 0 0
23 Locked QAM256 43 663000000 Hz 1.7 dBmV 38.6 dB 0 0
24 Locked QAM256 44 669000000 Hz 1.4 dBmV 38.2 dB 0 0

upstream is fine. also what is a good starting frequency to try. 

Thanks in advance