Back in March of 2013, I installed a Diamond K9000 Motorized Antenna Mount. Unfortunately it started acting up about five months ago after about 3.5 years of service mounted on a truck that leaves its garage about twice a week, and an antenna that has been raised/lowered less than 100 times. Needless to say I wasn’t happy.
I was even less happy when I opened the failed unit up and found that it obviously been filled with water at one point as many parts were heavily rusted, despite weep-holes intended to allow the water to drain. Another issue was discovering a cheaply made limit switch that turns the motor off when in the stowed position. This was very odd considering that a real snap switch was used for the other limit switch (a SPDT used in the raised position).
The unit was purchased new in early 2013. The final surprise was discovering that it had been fabricated in 2008 — meaning it had hung around in inventory for 5 years! Given the lack of quality of the broken limit switch, even having it sit around probably caused the contact to oxidize.
Given the cold weather I waited until spring to swap it out with a new one. This one appears to be new 2016 inventory. Hopefully it will last longer than the first one.