HP G71 lcd screen has stripe issues

Either that or the LCD. Only two options if a external monitor works.

Is it common for the LCD to go out before the LCD cable or does it just depend on brand?

neither, it all depends on how you use it.

If you gave your hinges hell and it stayed dirty and stuff its probably the cable.
If you dropped it a time or two, and always kept your brightness on high then its probably the LCD.

Go on amazon to find a replacement. Just so you know a expected price usually $75 for a LCD I charge $20 to replace one in my shop.

Very very true. Thanks for info. Will probably buy LCD cable first then get LCD screen if needed.