|Cleaning variable capacitor bearings
|There are often two related issues, one the bearing smoothness, the other the rotor connectivity to the frame of the capacitor. In many cases, there are separate grounding springs that bear on rotor plates. Make sure that both surfaces are clean and making good contact.
In some capacitors, the rotor grounding takes place through the bearings. If that is the case, only a conductive grease should be used. There are a number of brands available in the electrical department of good hardware stores, or at electrical supply houses.
|Using Ladder Line
|You definitely need to connect the shields together at each end, otherwise you are doing a completely different arrangement. The shields can be grounded at either, both or neither end in order to make the transition properly, but it is a good idea to ground at least one end if it is near your station ground. If you calculate the voltages on the line (based on the SWR and power level) and they are appropriate to usual coax lightning arrestors, and near your station ground, it is also a great spot do introduce lightning protection.