I haven't tried this on a R-134 system yet, but I have done it on my R-22 home HVAC. I had a small pin hole in the "A" coil. I called a friend that works for a HVAC supply house. He said that they have a product that is introduced into the system just like refrigerant is, but it acts like the products that you use in your radiator to stop leaks. It finds the hole and once it hits "air", it cystalizes. He brought a can over, put it in, charged my HVAC and I haven't had a leak or any problems for 3 years now.
He said that most HVAC companies won't tell you about it because they want to sell you a new system rather than just a service call. I'm not sure if it works with all refrigerant or just R-22. Surely you can do a little research online to find out.
Of course, the gutter guard mod can greatly reduce the risk of this happening again if your condensor is the culprit and was actually damaged from road debris. It could be something as simple as an o-ring or bad hose/hard line. As others have said, I would recommend taking it to a professional. It might cost a little more, but it will be troubleshot and repaired fast and with a warranty.