Random wierd multis on 1800 t-bred B

I think Ive posted about this before but I really need to get it sorted out soon so Ill ask again if anyone can help. My 1800 dlt3c t-bred B has the last 2 L3 bridges cut which should give me a default multi of 15. For some reason though I have a default of 17 and I cant go any lower. All I can get is 17 which is from selecting 7 and 9, 18 from 7.5 and 9.5 or 23 from selecting 8, 8.5, 10 or 10.5. The rest wont post at all. According to John C the resident multi expert this is probably due to the 2x bridge being locked high. I wanted to know if reconnecting the bridges would fix it and if so do I need to fill the pits I made cutting them with something conductive or non conductive? I know this is a long winded post and a strange problem but I need to fix this so I can sell the PC to my sister to buy myself a new one. I could sell her it with a 17x 117fsb but I dont think shed get the same performance as if I had it on something like 14 or 15x 133 and she is my sister so I aint gonna rip her off.