Map[Length, CoefficientList[ Numerator[ Together[ <<left hand side of your equation>>> ]]]
tells me your problem is a quartic polynomial in m with 14, 158, 537, 1220 and 1682 term coefficients for m^0, m^1, m^2, m^3 and m^4.
If I look at the size of the result of only
Solve[a0 + a1*m + a2*m^2 + a3*m^3 + a4*m^4 == 0, m]
and imagine substituting something with 1682 terms for a4, 1220 terms for a3, etc. and have all the interdependencies between terms in common between those coefficients then I have almost no hope of seeing a solution from Solve unless there is some astonishing simplification available.