Hi Drodders,
There are two things that strike me as a possible reason:
1) the temperature could be too high. I would suggest something around:
- Pre heater: 37C
- Print heater: 37/38C
- Post heater: 40/41C
Higher grade material is more susceptible to heat as it is thinner.
2) Check the pressure electronically. The two left hand side pinch rollers could have either no or low pressure.
3) Make sure the vinyl is loaded correctly (taught).
Points 2 and 3 apply to all vinyl so probably not going to be the issue if it is ok with other vinyl.
Just out of curiosity, what brand vinyl is it?