Modification indices in lavaan package when freeing some fixed parameters

Question

I'm doing a confirmatory factor analysis using lavaan package in R. I want to see change in my model fit when I free some fixed parameters to find some erroneously fixed parameters in my model. There is an option in summary() that shows some modification indices but they are about when you add some constraints to your model. I want to see change in model fit after I free some already fixed parameters. Could I do that in lavaan, if not have you any other suggestions ? I think you really don't need the code to answer this question if you ever would, nevertheless here's the code I used:

model.mydata <-
'F1 =~ V3+V5+V15+V29+V31+V38+V40+V42+V44+V46+V48+V64+V65+V66
 F2 =~ V13+V17+V36+V37+V53+V56+V60+V62+V67+V68+V74+V75
 F3 =~ V4+V7+V11+V18+V25+V30+V32+V47+V52+V77+V79
 F4 =~ V10+V20+V26+V34+V41+V58+V59+V70+V72+V73+V76'

fit <- cfa (model.mydata, data=mydata)

summary (fit,fit.measure=TRUE,modindices = TRUE)
fitMeasures(fit)