help with ohm reader

[sublime90]

ok about 2 weeks ago i installed my new laser and all was well untill tonight. where it decided to stop loading up games, so i turned the dvd pot (by hand) to the right and i keep adjusting it and i keep gettign disc read errors. now i think i should probably buy an ohm reader at radio shack but i dont know wich one to get or how to even use one. so any help at all is appreciated, if all else fails as a last resort i'll buy a new ps2 and a new mod chip and start over. but id rather not if i can still save my laser if possible and if someoen tells me how to use an ohm reader

thanks