Replace parts as required first and reassemble. Always reset hook to needle timing first.
Select straight stitch and turn the stitch length to a long stitch setting.
Replace old needle with a brand new of size 90. Use a standard sewing machine needle.
Turn hand wheel anticlockwise and stop when the needle point is 0.5mm above needle plate.
Turn the pre-loosened feed gears on the horizontal lower shaft by hand, watch feed movement as feed moves up above needle plate. As if to feed the fabric it starts to move rearward and under the needle plate. (during this process you may need to have one hand on the hand wheel, stopping the needle from moving from its 0.5mm position)
To adjust the feed. As soon as the feed dog teeth move below the needle plate tighten all gears.
Check by turning the hand wheel anticlockwise. Watch as the feed dog moves and just as the needle point lowers through the needle plate, the feed dog also disappears below the needle plate.