I removed the oil return line to install an oil line nacelle. The retainer came out eaisly enough but, I can't replace it. Is there some trick to replace the oil line retainer.

Thanks

 

It should just snap back into place. There is an 'O' ring and a plastic washer in front of the retainer. This is for an 06 heritage. You didn't specify what type of bike you had.

I would recommend a service manual and a parts book. Very helpful.