King's Lynn Stars have signed Mateusz Szczepaniak and Joe Screen, with Dakota North, Kyle Howarth and Jordan Frampton dropping out of the line-up.
Szczepaniak, a 25-year-old Pole, was set to join Poole Pirates this season but the deal fell through.
He will ride at number seven full-time in place of double-up riders North and Howarth.
Former under-21 world champion Screen, 27, usurps Frampton as David Howe's double-up partner.
The move comes off the back of a six-meeting losing streak for the Stars.
"We have been so close to earning league points in every single match we have ridden so far this season. But it has always been the matter of our number seven scoring too few points," said boss Rob Lyon.
"Now hopefully Mateusz will turn that difference around and Joe will be more than adequate covering for David when he is unavailable."