Electronic machines always will present a greater risk than manual machines due to exactly that. That being said, the price should not be a reflection of the quality of the machines. I'm surprised to see this thread and these comments. Pro's Pro is an extremely popular brand in Europe for all three types of their machines.
The reason prices on the Pro's Pro products are extremely low is due to just a few in the supply chain, cutting costs significantly. In all of our experience of dealing with the electronic Pro's Pro machines, it remains to be the type of machine we would recommend.
These machines are built to last and many stringers have racked up hundreds of racquets on these machines. If you're stringing several racquets a week, these machines are perfect.
I have the tx600a and it's been an absolute nightmare. This is my first machine as I'm 16 and only been stringing a year. I was pulled in by the price, an electronic machine for £400, bargain! Bought it and within 6 months I had to buy 2 totally new clamp bases, they were automatic but now I've got the normal ones.
Without knowing more on this issue, I can say that these clamps don't just suddenly stop working. I would be inclined to say that you did not adjust the clamp base with the Allen key. This is a maintenance issue which must be done from time to time.