(a) Grounds. A new trial may be granted to all or any of the parties and on all or part of the issues for any of the reasons for which rehearings have heretofore been granted in suits in equity in the courts of the Commonwealth. On a motion for a new trial, the court may open the judgment if one has been entered, take additional testimony, amend findings of fact and conclusions of law or make new findings and conclusions, and direct the entry of a new judgment. (b)Time for Motion. A motion for a new trial shall be served not later than 10 days after the entry of judgment. (c) Time for Serving Affidavits. When a motion for new trial is based upon affidavits they shall be served with the motion. The opposing party has 10 days after such service within which to serve opposing affidavits, which period may be extended for an additional period not exceeding 20 days either by the court for good cause shown or by the parties by written stipulation. The court may permit reply affidavits. (d) On Initiative of Court. Not later than 10 days after entry of judgment the court of its own initiative may order a new trial for any reason for which it might have granted a new trial on motion of a party. After giving the parties notice and an opportunity to be heard on the matter, the court may grant a motion for a new trial, timely served, for a reason not stated in the motion. In either case, the court shall specify in the order the grounds therefor. (e)Motion to Alter or Amend a Judgment. A motion to alter or amend the judgment shall be served not later than 10 days after entry of the judgment.