It sounds like more then one problem may be taking place here. The tingle you get when connecting jumpers with the radio off is not RF. An RF burn related to poor grounding would only take place while you were transmitting. For some reason it seems you have voltage between the chassis ground of your equipment and earth ground. Since the house has older wiring, there is a chance this problem may go away if you reverse the polarity of the AC line cord on the power supply by plugging it in the other way. This will only work in the plug is not polarized. If the plug is polarized you might want to check to be sure the outlet does not have the neutral wire reversed.
None of this is relates to your TVI or SWR problems. Unfortunately this may have more to do with your choice of antenna and perhaps its mounting location. The Ringo Rangers have long been noted for RFI issues as a result of their inability to decouple the antenna from the mast and coax cable. This can cause a significant amount of radiation to be present on both the mast and coax. Causing the SWR to fluctuate simply by moving the coax cable in some cases.
This coax and mast radiation could be intensified by the chain link fence the mast is attached to. Anytime we have loosely touching metals conducting RF such as the chain links in the fence, it can introduce more serious RFI issues due to the possibility of the poor connections rectifying the RF. Once the RF is rectified, it contains many more harmonics that can be reradiated off the fence. Since the Ringo is an end fed vertical with no radials, I suspect it is designed to use the mast and or coax as a counterpoise. In this case, isolating them may help with RFI but may also reduce your radiation efficiency and complicate your ability to achieve a good VSWR.
The Gain-Master might be a better choice for you if you're concerns are RFI, SWR, and the ability to cover both 10 and 11 meters. Although the cost and your relatively low mounting height may not be ideal with the GM. If you are willing to experiment with the Ringo, you may be able to get it to cover one band without the RFI and with a low SWR.
About the only effective way to decouple the mast and coax from the Ringo without killing the radiation efficiency by removing all of the counterpoise is to add some radials at the feedpoint. Three 1/4 wave radials attached to the ground at the feedpoint should be enough to do the trick. They can be anything from old steel whips to 1/4 wave wires with insulators and rope used as guy wires. They can be on any angle from 90 to 45 degrees however, the tap point on the tuning loop may require adjustment to match the impedance.
If that doesn't cure the problem 100% consider isolating the base from the mast and replacing the coax choke with ferrite beads of the correct mix for 27 MHz on the coax at the feedpoint. This type of choke often achieves a higher impedance to the CMC flowing on the coax without any of the resonance problems air wound choke can create.
None of this is relates to your TVI or SWR problems. Unfortunately this may have more to do with your choice of antenna and perhaps its mounting location. The Ringo Rangers have long been noted for RFI issues as a result of their inability to decouple the antenna from the mast and coax cable. This can cause a significant amount of radiation to be present on both the mast and coax. Causing the SWR to fluctuate simply by moving the coax cable in some cases.
This coax and mast radiation could be intensified by the chain link fence the mast is attached to. Anytime we have loosely touching metals conducting RF such as the chain links in the fence, it can introduce more serious RFI issues due to the possibility of the poor connections rectifying the RF. Once the RF is rectified, it contains many more harmonics that can be reradiated off the fence. Since the Ringo is an end fed vertical with no radials, I suspect it is designed to use the mast and or coax as a counterpoise. In this case, isolating them may help with RFI but may also reduce your radiation efficiency and complicate your ability to achieve a good VSWR.
The Gain-Master might be a better choice for you if you're concerns are RFI, SWR, and the ability to cover both 10 and 11 meters. Although the cost and your relatively low mounting height may not be ideal with the GM. If you are willing to experiment with the Ringo, you may be able to get it to cover one band without the RFI and with a low SWR.
About the only effective way to decouple the mast and coax from the Ringo without killing the radiation efficiency by removing all of the counterpoise is to add some radials at the feedpoint. Three 1/4 wave radials attached to the ground at the feedpoint should be enough to do the trick. They can be anything from old steel whips to 1/4 wave wires with insulators and rope used as guy wires. They can be on any angle from 90 to 45 degrees however, the tap point on the tuning loop may require adjustment to match the impedance.
If that doesn't cure the problem 100% consider isolating the base from the mast and replacing the coax choke with ferrite beads of the correct mix for 27 MHz on the coax at the feedpoint. This type of choke often achieves a higher impedance to the CMC flowing on the coax without any of the resonance problems air wound choke can create.
...runna pile-up on 6m SSB