Almost 9 out of 10 CTA trips are now paid for using the Ventra fare system, but with the first of three deadlines looming this week for riders who haven’t yet made the switch, breaking up with the old fare cards can be hard to do. On Pace, which is also transitioning to Ventra, about 60 percent of fares are currently paid using Ventra, the suburban bus agency said. There have been more than 153 million Ventra card taps to date on bus fare box readers and rail station turnstiles. What’s unclear is whether that reflects public confidence or resignation over the new fare system, which was plagued during its rollout late last summer by technical glitches and poor customer service in resolving problems. The failures by the Ventra contractor, Cubic Transportation Systems Inc., prompted the CTA to delay the full transition originally set for December from the old fare system to Ventra. Cubic, which was awarded a nearly half-billion-dollar contract with the CTA to launch and manage Ventra, has consistently met most of the performance standards in the contract since January, CTA officials said….