FA3T1102singer serial number

Not quite sure since the symptoms are not clear. "Bumpy stitches from bobbin"--does that mean there were thread nests on the bobbin side of the fabric? That is thread nesting or bird nesting resulting usually from mis-threading, upper thread not completely seated in tension disk, or upper tension too loose. Remove the upper thread from the machine. ALWAYS RAISE the presser foot and rethread from the beginning--verify the thread path is correct. Set the upper tension to the midway point between high & low number and retest the machine. (Upper tension may need to be tweaked because fabric, thread, and age of the machine will have an affect.)

Check that the bobbin is wound smoothly--no lumps, bumps, or thread ends/pieces sticking out of the bobbin. Check that the bobbin is installed in the bobbin case correctly (turning the proper direction) and the bobbin tension is threaded completely.

If the upper thread is not picking up the bobbin thread, make sure to install a brand new needle. (I don't try to straighten or "fix" damaged needles. With today's computerized machines, it may cause more damage than a new needle would cost. That may work on the old mechanical machines like the Singer Featherweights, but my machines are too important to risk for the price of a needle.) If it still won't pick up the bobbin thread, then the machine's timing has probably been knocked out of alignment. Search for sewing machine timing or take it for service.

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Make sure to use a brand new needle.
ALWAYS RAISE the presser foot when threading.
Unthread and re-thread from the beginning.
Verify the thread path is correct.
Set the upper tension to midway between High & Low numbers.
Verify the bobbin is loaded and threaded correctly in the bobbin case.
Begin sewing slowly and check the result. The upper tension can be tweaked so the upper & bobbin threads meet in the middle of the fabric.

If it is still not working properly, the machine may be out of time and require service.

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Install a brand new needle. A bent/dull/damaged needle sometimes will not pick up bobbin thread.

Check that the needle is installed facing the correct direction.

Also check that the bobbin is wound smoothly, the bobbin is turning the correct direction in the bobbin case, and the bobbin tension is threaded correctly.

If it still will not pick up the bobbin thread, there is most likely a timing issue, ie the needle is arriving at the wrong time to intercept the bobbin thread. Search the internet for sewing machine timing discussions or take it for service.

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First, install a brand new needle. Used/worn/bent needles will sometimes fail to pick up the bobbin thread.

Make sure the bobbin is installed correctly in the bobbin case.

If it still will not pick up the bobbin thread, most likely the machine is out of time (the needle arrives at the incorrect time to intercept the bobbin thread). Take it for service or search the internet for web sites or videos dealing with sewing machine timing.

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Do this by turning the wheel by hand. The bobbin thread will make a small loop on the way up. Move something thin from front to back, catching the top thread under the needle and the bobbin loop thread will come out. Move both threads towards the back and go!

try changing the needle to one that will work with heavier thread
you may have to change the bobbin to heavier thread also
try adjusting the tension also

1.check needle to see if it's bent or blunt end
2.check bobbin & bobbin case for lint or loose thread
3.could be a timming problem- would have to be serviced

Refer to the manual to be sure the bobbin is feeding the thread in the correct direction.

wont pick up thread from bobbin

could be your tension try it set at number 4