To access them, you'd need to remove the transmission from the vehicle. This is a significant job requiring specialized tools and transmission expertise. It's not something a typical DIYer would undertake.
If you're experiencing transmission problems, it's best to take your PT Cruiser to a qualified mechanic or transmission specialist. Trying to diagnose and repair transmission issues without the necessary knowledge and tools can cause further damage. They can properly diagnose the problem (which might not even be a faulty solenoid) and repair it correctly.