I haven't done this for years, so can't be sure you can still do it, but if you have an important recording with a glitch that causes transfer problems, you can
1. transfer the program up until the glitch.
2. pause the program on the original Tivo just after the glitch.
3. transfer the program from the pause point. Depending on the transfer program, you may get this choice - you should get it for a tivo-to-tivo transfer, so if the end destination is a PC or Mac, you can transfer the second half to another TiVo and then transfer to the PC (and presumably use editing software to join the halves.)
Obviously a lot of work, but may occasionally be worth it.
TiVo Roamio:Felix TiVo Premiere:Bob TiVo XL4:Fred TiVo HDXL:Sharon TiVoHD:Susan