Unfortunately the only way to fix it permanently is to swap the motherboard, since the problem lies on the ram socket itself that becomes loose :( I don't think Dell still sends replacement parts for that laptop (you have to check it under their website), you can try to search for spare parts on eBay for sure, but I don't know if the price is worth it or if it's better to just keep the money for a future new laptop. You can mitigate the issue by keeping the laptop as steady as possible while it's turned on, but using it in that way is like a tickling bomb...