Robert Lambie wrote::lol1:
my own opinion, if you have a machine with so many faults, you have a faulty machine. simple as that...
im using the same machine but wider and never had any problems what so ever...

Outline, I'd agree and say you have a lemon mate. How long have you had it? I'd seriously pressure your dealer to replace it, certainly here we have laws that will assist you in that. May be worth a talk to a solicitor first.
Also, I'd get a second opinion from another cadet owner. See if they will come over and run the machine with files they know to be good. They may have enough experience to see what may be going wrong if they have had a machine for a while.
I had lines in the prrint of my Roland, and had the warranty people out to check it out. They had no idea why it was doing it because it was intermittant at the time.
Finally had a 'heart to heart' with my supplier and he sent out his rep who had is own shop before he became an employee.
He picked the black head was faulty, changed it and it has never printed so good. It must have been faulty from the start, but I knew no better.
My supplier even covered the costs himself because Roland would not pay as they did not diagnose it. Luckily I am a big customer and he was happy to support me, but the point is, if I had not found someone with practical experience I would have been an irate or very disappointed customer by now.
The first thing I would do tho is a 'heavy' clean. Costs a bit, but that is the first this a repair guy will do anyway. Vectorwise has given you good advice here, I'd follow his suggestions before going any further.
Hope it works out,
Cheers
Shane