reading tape on Centos 7

I am trying to read a tar tape on Centos 7 which was written on Centos 5. I used blocking factor 2048. I can read tapes written with blocking factor 1024, but not 2048. Attempting to read the tape with dd (something like dd if=/dev/nst0 bs=1M | tar tvf – ) doesn’t work either, which suggests something different about the st driver. Any advice? Centos 5 is kernel 2.6.18, Centos 7 is kernel 3.10.0.