Shimano XTERA Service advice.

I recently sent my Shimano XTERA reels via a so called reputeable angling shop for service. On the first use of my reels the one reel has a rough retrieve at the start of the up stroke making a whirr whirr sound. Many moons ago I read a thread in Sealine about the same problem and the solution but, since then age stepped in and I forgot the solution and I will be damned to find that thread again. Pse help with advice at what I could do to rectify. I do not want to take it back to get fixed a second time. They worked perfectly well before I made the mistake to send them for serviceing.