1st guess, pinched optics.
2nd guess wrong laser collimator used. If it's only 1mW the beam is possibly not strong enough to go the distance through a 10" tube. 5mW laser collimator will do the trick (in my experience) or a laser specifically made for newtonians. It's better to double check collimation with a Cheshire after using a laser to confirm accuracy anyway.
Perhaps it's a good idea to contact the previous owner & ask what he/she used, maybe(?).
Hope this info was helpful or useful.
Note, I find it interesting no one with more experience than myself did not post a help message
.
Good luck
Guy