Even with the proposed modifications, there's no guarantee it's safe. You could hi-pot test it, which would increase the confidence level of it being safe, but that won't rule out other design flaws, such as cheap insulation in the transformer, which fails when it reaches normal operating temperature.
I wouldn't recommend anyone buys anything dangerous, then modifies it to make it less hazardous. Don't buy it and if you've already bought it, return it! In many jurisdictions, you're still entitled to return a product for a full refund because it's unsafe, even if the warranty period has expired.
Buying cheap, crappy, dangerous products, with the intention of fixing them is immoral. No one should be allowed to profit from selling products which can put the lives of unsuspecting buyers and other who might come into contact with them in danger. If it goes wrong, and injures someone else, then you have a higher risk of being liable, since you knew it was dangerous in the first place.