My customer have machine Ricoh Mp4000, the problem was sc350. when they done several copies, the copies is ok but sc350 occurs & coming unexpectedly. When i open the right cover i saw a patch (line)on the transfer belt. The drum is clean. Help me for solving this problem thanks. i replaced drum, developer,cleaning blade, charge roller +cleaner brush, transfer belt +cleaning blade. The Id sensor stay between 6.5 to 6.3. dont know what to do?