Network Adapter Issue - Acer Aspire 5749Z

Recently, my laptop wireless signal strength is only one-two bars of service despite the fact that I'm directly beside the router and other laptops show full strength. I used to have full strength in the past, however I suspect a recent network adapter issue may be the culprit. I've tried multiple wireless networks and all yield the same result. At times, sometimes the signal strength is so low, I only have limited connectivity. What can I do to further troubleshoot the laptop myself? And if replacement parts are needed, where can I purchase them or have them installed? Additionally, I can connect directly to the router using a cable without any connection issues.