"We need to redesign certain things," Red Bull's Marko told Germany's Auto Bild.
"It's annoying, but I keep remembering that in 2010 we also did not test in the first week."
Red Bull, and the now quadruple-consecutive world champion Sebastian Vettel, ultimately went on to win the 2010 title.
This time, however, the problems appear to be more serious. Auto Bild quoted technical chief Newey as admitting he has "no idea" if he can solve the RB10's problems to his satisfaction.
Marko, though, is confident.
"Adrian's concept is good in principle -- I think our car is very elegant, and beautiful cars are usually also fast."