Malfunction of helicoid

Even a piece of small dust like chiselled metal powder or fiber dusts could cause fatal dysfunction of focusing mechanical movement, yes, that happened last night on SLR Minolta Rokkor 35/2,8 that had been modified to adopt on EOS mount. Probably some dust might have gotten into the helicoid groove in the way of processing. The importance is feel on focusing ring of manual device, the viscosity of lubricant there is indispensable item, not so soft but not too hard as not to produce backlash on the barrel straight moving guide. Unfortunately engraved scratches there formed on aluminum alloy might do harm on smooth movement of focusing ring even after cleaning? Because a focal length of35mm lens on EOS APS-C imaging format plays as a standard angle of view, this one should be survived even at any efforts. Micro particulate Teflon powder would be helpful for the purpose?