The Twin Comanche is the best light twin ever built. There has been no other light twin that has the range, payload, and speed on that horsepower and fuel burn.
Having said that most are around 40 years old and that means 40 years of wear. Though nothing that good maintenance doesn't over come.
The Comanche has a strong well built airframe, but there are one or two areas that need good maintenance though probably no more so than other simlar types or aircraft. One area that needs to be well cared for is the undercarriage. It seems that some owners do scrimp on maintenance or some engineers don't fully comply with or understand the requirements for the 1000 hour undercarriage inspections.
The fuel selectors have been flagged as a potential problem area, they can be rebuilt/repaired though if there is too much corrosion they may need replacment. The main problem is the selectors also contain the fuel filter and water can collect in the fuel selector/filter. If this water is left there too long corrosion can result.
The big secret here is to do thorough fuel drains prior to flight but also after that last flight of the day drain the bowls on the selectors to attempt to drain any water that may have collected during flight. Surface tension can cause some water to be retained in the filter so it is absolutely essential to remove the fuel bowls every 50 hours as specified in the maintenance schedule (and I would suggest every 2 months) and remove and clean the filters and remove any retained droplets of water.
As with any 40 year old aircraft do expect to have teething troubles as a new owner. One issue with any peice of machinery is how much use it gets. Very often the niggling issues we experience with a piece of machinery is due to a lack of use. Things gum up and stop work through disuse. I believe that an aircraft needs to be flown at least every two weeks, even if it is only a couple of circuits.
PM me if you have specific questions.