Personally I'd forget attempting to buy a mod that can convert from boro to 'normal' tank mode. The chances of you wanting to swap from boro to rta/rda when you are away from home is probably nil unless you habitually carry spare tanks for every occasion when you go out. If you are at home. If you decide to use an rta/rda just pick up one of the mods you already own and put a battery in it.
The only multi purpose boro/rta things I've seen are adapters that you stick in the boro compartment so you can screw a tank into the top of the mod. If you use this type of adapter you will be able to use a boro mod BUT it will then lose the pocketable format of a boro device and will turn into another box with a tank perched on top of it.
I've seen one other high end mod that can convert to an SBS or Boro - this thing is as ugly af - and it relies on press fit electrical connectors to carry the current to the 510/RBA pos and neg. If you have problems now with the 'wheel' (do you mean a screw down battery positive connector) you won't believe the grief press together connections can give. They work fine when assembled and left alone - but when constantly taken apart and reconnected they aren't good.
If the 'wheel' causing problems is the battery contact IS the positive battery connector - have you removed it, cleaned it (preferably with metal polish) and re-assembled? If it is coated a pretty colour - make sure the connecting surface is NOT coated -if it is remove it as paint/enamel on an electrical connection WILL cause problems. Give the battery connecters a clean as well.
There is one other possibility that could be causing issues with your mod. I seem to remember Bogan making a vid about electrical connection issues with the board i can't remember if this applies to the stubby or empire mod or both... but if the Stubby has an easy change board - apparently the board is designed to be changed easily by the user and the pos and neg wires aren't soldered to the board - they are held down by (gold I think) screws. Apparently making sure these screws are tight can resolve many issues.
Good luck.