42'' plasma with fuzzy/sparkly picture?

(timecomputers.com branded) 42" OMEGA 615W plasma with a samsung panel. bought it secondhand 'as is' with a fault. switches on as it should but the picture is mostly fuzzy and speckly/sparkly. also, when anything is on the screen such as the menu, it takes a while to disappear after going back to what you are watching ?burning/ghosting?
the main fault is the fuzzy/sparkly picture. it is watchable but certainly not right. it is exactly the same no matter what input is used ie: scart with digital cable box or DVD etc... so i don't think it's an input problem. the speckly/sparkly/fuzzy fault shows on the screen just with the set switched on with nothing inputted. any advice would be very much appreciated because i want to know enough not to get ripped off when i take it to a repair shop.
thankyou...