You'd probably get a better response click here and the Registration is almost immediate. It's an independent Sky User forum with lots of people who know about satellite reception.
Basically I'd guess you should at least have the dish realigned and seriously consider a new LNB. Neither need be expensive, if you can DIY it you'll find lots of dish/LNB combinations on ebay.
The Sky signal is very strong and so you're problems suggest you are loosing the strength/quality somewhere in your system. It could be the receiver getting old, it could be the cable to the receiver, it could be the connectors on the cable, it could be the LNB, it could be the dish alignment.